LIBRARY 

OF    THE 

UNIVERSITY  OF  CALIFORNIA, 
Class 


INTRODUCTION 


TO   THE 


RARER    ELEMENTS. 


PHILIP  E.  BROWNING,   PH.D., 

Assistant  Professor  of  Chemistry^  Kent  Chemical  Laboratory, 
Yale  University. 


FIRST   EDITION. 
FIRST    THOUSAND 

TJT. 

/TV 

Or 

NEW  YORK: 

JOHN  WILEY  &  SONS. 

LONDON  :  CHAPMAN  &  HALL,  LIMITED. 

1903. 


•WH1N39 


Copyright,  1903, 

BY 
PHILIP  E.  BROWNING. 


ROBERT  DRUMMOND,  PRINTER,  NEW  YORK. 


A\ 


PREFACE. 


THIS  small  volume,  prepared  from  material  used  by  the 
author  in  a  short  lecture  course  given  at  Yale  University, 
is  intended  to  serve  as  a  convenient  handbook  in  the  intro- 
ductory study  of  the  rarer  elements ;  that  is,  of  those 
elements  which  are  not  always  taken  up  in  a  general  course 
in  chemistry.  No  attempt  has  been  made  to  treat  any  part 
of  the  subject  exhaustively,  but  enough  references  have 
been  given  to  furnish  a  point  of  departure  for  the  student 
who  wishes  to  investigate  for  himself.  Experimental  work 
has  been  included  except  in  the  case  of  those  elements  which 
are  unavailable,  either  because  of  their  scarcity  or  because 
of  the  difficulty  of  isolating  them. 

The  author  has  drawn  freely  upon  chemical  journals  and 
standard  general  works.  In  his  treatment  of  the  rare  earths 
he  has  made  especial  use  of  Herzfeld  and  Korn's  Chemie 
der  seltenen  Erden  and  Truchot's  Les  Terres  Rares,.  works 
which  he  gladly  recommends.  He  gratefully  acknowledges 
the  valuable  assistance  of  his  wife  in  preparing  this  ma- 
terial for  the  press. 

NEW  HAVEN    CONN.,  April,  1903. 

iii 


115402 


JOURNALS  CITED. 


American  Chemical  Journal. 

American  Journal  of  Science. 

Analyst,  The. 

Annalen  der  Chemie  und  Phar- 
macie. 

Annales  de  Chimie. 

Annales  de  Chimie  et  de  Phy- 
sique. 

Annalen  der  Physik  und  Chemie. 

Atti  del  la  R.  Accademia  dei 
Lincei,  Roma. 

Berichte  der  Deutschen  che- 
mischen  Gesellschaft. 

Bulletin  de  1'Academie  imperiale 
de  St.  Petersbourg. 

Bulletin  de  la  Socie"te  chimique 
de  Paris. 

Bulletin  of  the  U.  S.  Geological 
Survey. 

Chemisches  Central-Blatt. 

Chemische  Industrie. 

Chemical  News. 

Chemiker-Zeitung. 

Comptes  rendus  de  1' Academic 
des  sciences  (Paris). 

Crell  's  Annalen. 

Engineering  and  Mining  Journal. 

Jahresbericht  der  Chemie. 

Journal  of  the  American  Chemi- 
cal Society. 

Journal  of  the  London  Chemical 
Society. 

Journal  of  Physical  Chemistry. 


Journal  fiir  praktische  Chemie. 

Journal  of  the  Russian  Physical- 
Chemical  Society. 

Journal  of  the  Society  of  Chemi- 
cal Industry. 

Klaproth's  Beitrage. 

Kongl.  Vetenskaps  Academiens 
Handlingar  (Stockholm). 

Liebig's  Annalen  der  Chemie. 

Monatshefte  fiif  Chemie. 

Nicholson 's  Journal. 

Philosophical  Magazine. 

Philosophical  Transactions  of  the 
Royal  Society. 

Poggendorff 's  Annalen. 

Proceedings  of  the  American 
Academy  of  Arts  and  Sciences. 

Proceedings  of  the  Royal  So- 
ciety (London). 

Rendiconto  dell'  Accademia  delle 
Scienze  Fisiche  e  Matematiche, 
Napoli. 

Science. 

Sitzungsberichte  der  kaiserlichen 
Akademie  der  Wissenschaften. 
Mathematisch  -  Naturwissen- 
schaftliche  Classe  (Wien). 

Zeitschrift  fiir  analytische 
Chemie. 

Zeitschrift  fiir  angewandte 
Chemie. 

Zeitschrift  fiir  anorganische 
Chemie. 


INDEXES  TO  THE  LITERATURE  OF  CERTAIN 
ELEMENTS. 


Caesium,   Rubidium,   and  Lithium,   Index   to   the   Literature  of; 
Fraprie.     In  preparation. 

Cerium,  Index  to  the  Literature  of  (1751-1894);  Magee.     Smith- 
sonian Misc.  Coll.  (1895),  No.  971. 

Columbium,  Index  to  the  Literature  of  (1801-1887);    Traphagen. 
Smithsonian  Misc.  Coll.   (1888),  No.  663. 

Didymium,   Index  to  the  Literature  of   (1842-1893);    Langmuir. 
Smithsonian  Misc.  Coll.  (1894),  No.  972. 

Gallium,  Index  to  the  Literature  of  (1876-1903) ;        }    Browning. 

Germanium,  Index  to  the  Literature  of  (1886-1903);  >   In  prepara- 

Indium,  Index  to  the  Literature  of  (1863-1903);         )        tion. 

Lanthanum,    Index    to    the    Literature    of    (1839-1894);    Magee. 
Smithsonian  Misc.  Coll.   (1895),  No.  971. 

Lithium,  vid.  Caesium. 

Niobium  or  Columbium,   vid.   Columbium. 

Platinum   Metals,    Bibliography   of  (1748-1897);    Howe.     Smith- 
sonian Misc.  Coll.  (1897),  No.   1084. 

Rubidium,  vid.  Caesium. 

Selenium  and  Tellurium,  Index  to  the  Literature  of;  G.  A.  Smith. 
In  preparation. 

Tellurium,  vid.  Selenium. 

Thallium,  Index  to  the  Literature  of  (1861-1896);  Doan.     Smith- 
sonian Misc.  Coll.   (1899),  No.   1171. 

Thorium,  Index  to  the  Literature  of;  Joiiet.     Smithsonian  Misc. 
Coll.     In   press. 

Titanium,  Index  to  the  Literature  of  (1783-1876);   Hallock.     An- 
nals of  the  N.  Y.  Academy  of  Sciences  (1876),  I,  53. 

Uranium,  Index  to  the  Literature  of  (1789-1885);  Bolton.     Smith- 
sonian Report  for  1885,  Part  I,  915. 

vii     • 


viii      INDEXES  TO  THE  LITERATURE  OF  CERTAIN  ELEMENTS. 

Vanadium,    Index    to    the    Literature  of  (1801-1877);    Rockwell. 

Annals  of  the  N.  Y.  Academy  of  Sciences  (1879),  J»  I33- 
Yttrium  Group,  Index  to  the  Literature  of  the  Rare  Earths  of; 

Dales.     In   preparation. 
Zirconium,    Index   to   the   Literature   of    (1789-1898);    Langmuir 

and  Baskerville.     Smithsonian  Misc.  Coll.  (1899),  No.  1173. 

Attention  is  called  also  to  the  following  monographs: 

Die  Chemie  des  Thoriums;  Koppel.  Sammlung  chemischer  Vor- 
trage,  Band  VI.  Pub.  by  Ferd.  Enke,  Stuttgart,  1901. 

Studien  iiber  das  Tellur;  Gutbier.  Pub.  by  C.  L.  Hirschfeld,  Leip- 
zig, 1902. 

La  Chimie  de  L 'Uranium  (1872—1902);  Oechsner  de  Coninck. 
Pub.  by  Masson  et  Cie.,  Paris,  1902. 

Die  analytischer  Chemie  des  Vanadins ;  Valerian  von  Klecki.  Pub. 
by  Leopold  Voss,  Hamburg,  1894. 


HE   RARER  ELEMENTS, 


CAESIUM,  Cs,   133. 

Discovery.  Caesium  was  discovered  in  1860  by  Bun- 
sen  and  Kirchhoff  while  they  were  engaged  in  the  spectro- 
scopic  examination  of  a  mother-liquor  from  the  waters  of 
Durkheim  spring  (Pogg.  Annal.  cxm,  337;  Chem.  News  n, 
281).  After  the  removal  of  the  strontium,  calcium,  and 
magnesium,  by  well-known  methods,  and  of  the  lithium 
as  far  as  possible  by  ammonium  carbonate,  the  mother- 
liquor  was  tested,  and  gave,  in  addition  to  the  potassium, 
sodium,  and  lithium  lines,  two  beautiful  blue  lines  never 
before  observed,  near  the  strontium  blue  lines.  Bunsen 
gave  the  name  Caesium  to  the  newly  discovered  element, 
from  the  Latin  caesius,  the  blue  of  the  clear  sky. 

Occurrence.  Caesium  is  found  in  combination  as 
follows  : 

(i)   In  minerals: 
Pollucite,  H2Cs4Al4(SiO3)9,  contains  3i~37%*Cs2O. 


Beryl,  Be3Al2(SiO3)6,  contains  0-3%  Cs2O. 

(2)  In  certain  mineral  waters,  among  which  are  Durk- 
heim (  i  liter  contains  about  '0.21  mg.  RbCl  and  0.17  mg. 
CsCl),  Nauheim,  Baden-Baden,  Frankenhausen,  Kreuz- 
nacher,  Bourbonne  les  Bains,  Monte  Catino,  Wheal  Clifford. 

Extraction.  Of  the  methods  in  use  for  the  extraction 
of  caesium  the  following  may  serve  as  examples: 

*  In  the  tabulation  of    percentages  the  nearest  whole  numbers  have 
generally  been  used  in  this  book. 


3  THE  RARER  ELEMENTS. 

(1)  From  pollucite.     The   finely  powdered  mineral  is 
decomposed  on  a  water-bath  with  strong  hydrochloric  acid. 
To  the  acid  solution  antimony  trichloride  is  added,  which 
precipitates  the  double  chloride  of  antimony  and  caesium 
(3CsCl-2SbCl3)    (Wells,    Amer.    Chem.    Jour,    xxvi,    265). 
Or  the  acid  solution  may  be  treated  with  a  solution  of  lead 
chloride    containing    free    chlorine.     This    precipitates    a 
double  chloride  of  caesium  and  tetravalent  lead  (2CsCl  •  PbCl4) 
(Wells,  Amer.  Jour.  Sci.  [3]  XLVI,  186). 

(2)  From  pollucite  or  lepidolite.     The  mineral  is  heated 
with  a  mixture  of  calcium  carbonate  and  calcium  chloride, 
and  the  fused  mass  is  cooled  and  extracted  with  water. 
The  liquid  is  then  evaporated  to  a  small  volume,  and  sul- 
phuric acid  is  added  to  precipitate  the  calcium  as  the  sul- 
phate.    After  nitration,  evaporation  is  continued  until  the 
greater  part  of  the  hydrochloric  acid  has  been  expelled. 
Sodium  or  ammonium  carbonate  is  then  added  to  complete 
the  removal  of  the  calcium  salt.     Upon  the  addition  of 
chloroplatinic  acid  the  caesium  and  rubidium  are  precipi- 
tated as  the  salts  of  that  acid.     By  the  action  of  hydrogen 
upon  these  salts  the  platinum  is  precipitated,  while  the 
caesium  and  rubidium  chlorides  are  left  in  solution. 

(3)  From  lepidolite.     The  mineral  is   decomposed  by 
heating  with  a  mixture  of  calcium  fluoride  and  sulphuric 
acid   (vid.  Experiment   i). 

The  Element.  A.  Preparation.  Elementary  caesium 
may  be  obtained  (i)  by  heating  caesium  hydroxide  with 
aluminum  to  redness  in  a  nickel  retort  (Beketoff,  Bull. 
Acad.  Petersburg  iv,  247) ;  (2)  by  heating  caesium  hy- 
droxide with  magnesium  in  a  current  of  hydrogen  (Erd- 
mann  and  Menke,  Jour.  Amer.  Chem.  Soc.  xxi,  259,  420); 
(3)  by  heating  caesium  carbonate  with  magnesium  in  a 
current  of  hydrogen  (Graefe  and  Eckardt,  Zeitsch.  anorg. 
Chem.  xxn,  158). 

B.  Properties.    Caesium,  the  most  positive  of  the  metals, 


CAESIUM.  3 

is  silvery  white  and  soft.  It  takes  fire  quickly  in  the  air, 
burning  to  the  oxide.  It  melts  at  26°  C.  Like  the  other 
alkaline  metals  it  decomposes  water.  Determinations  of 
its  specific  gravity  range  from  1.88  to  2.4. 

Compounds.     A.      Typical    forms.     The    following    are 
typical  compounds  of  caesium: 
Oxide,  Cs2O. 
Hydroxide,  CsOH. 
Carbonates,  Cs2CO3;  CsHCO3. 
Chloride,  CsCl. 
Double    chlorides,    AgCl-CsCl;    AgCl-2CsCl;    HgCl2-CsCl; 

HgCl2-2CsCl;  HgCl2.3CsCl;  2HgCl2-CsCl;  5HgCl2-CsCl; 

PbCl4-2CsCl;    PbCl2.4CsCl;    PbCl2-CsCl;    2PbCl2-CsCl; 

2BiCl3-3CsCl;  BiCl3-3CsCl;  CuCl2-2CsCl;  CuCl2-2CsCl  + 

2H2O;   2CuCl2-3CsCl  +  2H2O;   CuCl2-CsCl;   Cu2Cl2-CsCl; 

Cu2Cl2  -  3CsCl ;        Cu2Cl2  -  6CsCl  +  2H2O ;        CdCl2  •  2CsCl ; 

CdCl2-CsCl;    2AsCl3-3CsCl;    2SbCl3-3CsCl;    SnCl2-CsCl; 

Fe2Cl6-6CsCl;  CoCl2-3CsCl;   CoCl2-2CsCl;   CoCl2-CsCl  + 

2H2O ;        NiCl2  •  2CsCl ;        NiCl2  •  CsCl ;        MnCl2  •  2CsCl ; 

2MnCl2  •  2CsCl  +  sH2O ;  MnCl2  •  2CsCl  +  3H2O ;  MnCl2  •  CsCl 

+  2H2O;  MnCl2-2CsCl  +  H2O;  ZnCl2-3CsCl;  ZnCl2-2CsCl; 

MgCl2-CsCl-|-6H2O;    AuCl3.CsCl;    AuCl3-CsCl  +  o.sH2O; 

PtCl4-2CsCl;    PtCl2-2CsCl;    PdCl2-2CsCl;    TeCl4-2CsCl; 

T1C13  •  3CsCl  +  H2O ;      T1C13  -  2CsCl ;      T1C13  •  2CsCl  +  H2O ; 

2TlCl3-3CsCl. 

Bromides,  CsBr;  CsBr3;  CsBr5. 
Double  bromides,  HgBr2  -  CsBr ;  HgBr2  -  2CsBr ;  HgBr2  -  3CsBr ; 

2HgBr2-CsBr;  PbBr2-4CsBr;  PbBr2-CsBr;  2?bBr2-CsBr; 

CuBr2-2CsBr;  CuBr2-CsBr;  CdBr2-3CsBr;  CdBr2-2CsBr; 

CdBr2  -  CsBr ;  2  AsBr3  •  3CsBr ;  CoBr2  •  3CsBr ;  CoBr2  •  2CsBr ; 

NiBr2  -  CsBr ;  ZnBr,  -  3CsBr ;  ZnBr2  •  2CsBr ;  MgBr2  -  CsBr  + 

6H2O;     AuBr3-CsBr;      TeBr4-2CsBr;      2TlBr3  •  3CsBr ; 

TlBr3-CsBr. 

Iodides,  Csl;  CsI8;  CsI5. 
Double  iodides,  HgI2-CsI;         HgI2.2CsI;         HgIa.3CsI; 


4  THE  RARER  ELEMENTS. 

2HgI2.CsI;3HgI2.2CsI;PbI2.CsI;CdI2.3CsI;CdI2.2CsI; 

CdI2-CsH-H2O;     2AsI3.3CsI;     CoI2-2CsI;     ZnI2-3CsI; 

ZnI2-2CsI;  TeI4-2CsI;  TlI3-CsI. 
Mixed   halides,    HgCs3Cl3Br2;      HgCs2Cl2Br2;      HgCsClBr2; 

Hg5CsClBr10;      HgCs3Br3I2;      HgCs2Br2I2;      HgCsBrI2; 

HgCs2Cl2I2;  PbCs4(ClBr)6;  PbCs(ClBr)3;  Pb2Cs(ClBr)5. 
Double  fluorides,  20sF  -  ZrF4 ;  CsF  - ZrF4  +  H2O ;  2CsF  •  3ZrF4  -f 

2H20. 

lodates,  CsIO-3;  2CsIO3.I2O5;  2CsIO3-I2O5  +  2HIO3. 
Nitride,  CsN3  (Jour.  Amer.  Chem.  Soc.  xx,  225). 
Nitrates,  CsNO3;  3CsNO3-Cs(NO3)3  +  H2O. 
Sulphates,  Cs2SO4;  CsHSO4;  Cs2S2O7;  Cs2O-8SO3. 
Alums,  CsAl(SO4)2  +  i2H2O;        Cs2SO4-Mn2(SO4)3  +  24H2O; 

Cs2S04.Ti203.3S03  +  24H20. 
Fluosilicate,  Cs2SiF6. 
Chromates,  Cs2CrO4;  Cs2Cr2O7. 
Chloroplatinate,  CsPtCl6. 

B.  Characteristics.  With  few  exceptions  the  caesium 
compounds  are  soluble  in  water.  They  closely  resemble 
the  potassium  and  rubidium  compounds,  being  for  the 
most  part  isomorphous  with  them.  A  comparison  of  the 
solubilities  of  the  alums  and  also  of  the  chloroplatinates 
of  the  three  elements,  at  a  temperature  of  15°-!  7°  C.> 
follows : 

100  parts  of  water  will  dissolve 

CsAl(SO4)2  +  i2H2O,    0.62  parts;  Cs  2PtCl6,  0.18  parts. 
RbAl(SO4)2  +  i2H2O,    2.3o     "       Rb2PtCl6,  0.20     " 
KA1(S04)2  +i2H20,  13.50     "         K2PtCl6,  2.17     M 
Among  the  important  insoluble  salts  are  the  chloroplati- 
nate  (Cs2PtCl6),  the   alum   (CsAl(SO4)2  +  i2H2O),  and   the 
double    chlorides    with    tetravalent    lead     (PbCl4-2CsCl), 
tetravalent    tin    (2CsCl-SnCl4?),    and    trivalent    antimony 
(3CsCl-2SbCl3).     The    salts    of    caesium    color    the    flame 
violet.     The    spectrum   shows   two    sharply   defined   lines 
in  the  blue,  designated  on  the  scale  as  Csa  and  Cs/?. 


RUBIDIUM.  5 

Estimation,  Separation,  and  Experimental  Work.  Vid.  Ru- 
bidium. 

RUBIDIUM,  Rb,  85.4. 

Discovery.  Rubidium  was  discovered  by  Bunsen 
and  Kirchhoff  in  1861,  by  means  of  the  spectroscope,  in 
the  course  of  some  work  upon  a  lepidolite  from  Saxony 
(J.  B.  (1861),  173;  Chem.  News  in,  357).  The  alkaline 
salts  had  been  separated  by  the  usual  methods  and  pre- 
cipitated with  platinic  chloride.  The  precipitate,  when 
examined  with  the  spectroscope,  showed  at  first  only  the 
potassium  lines.  When  it  had  been  boiled  repeatedly 
with  water,  however,  the  residue  gave  two  violet  lines 
situated  between  the  strontium  blue  line  and  the  potas- 
sium violet  line  at  the  extreme  right  of  the  spectrum. 
These  increased  in  strength  as  the  boiling  continued,  and 
with  them  appeared  several  other  lines,  among  which 
were  two  almost  coincident  with  the  potassium  red  line  (a) 
at  the  extreme  left.  These  lines,  observed  for  the  first 
time,  marked  the  discovery  of  an  element ;  because  of  their 
color  Bunsen  gave  it  the  name  Rubidium,  from  the  Latin 
rubidus,  the  deepest  red. 

Occurrence.  Rubidium,  like  caesium,  is  widely  distrib- 
uted, but  in  very  small  quantities.  It  is  found 

(i)  In  minerals: 

Lepidolite*     R3Al(SiO3)3,        contains  0.7-3.0%  Rb2O. 

Leucite,  KAl(SiO3)2,  "         traces 

Spodumene,  '  LiAl(SiO3)2, 

Triphylite,       Li(Fe,Mn)PO4, 

Lithiophilite,  Li(Mn,Fe) PO4, 

Carnallite,       KMgCl3-6H2O, 

Mica  and  orthoclase  contain 

*  The  more  important  mineral  sources  are  indicated  by  italics. 


6  THE  RARER  ELEMENTS. 

(2)  In  certain  mineral  waters,  among  which  are  the 
following:  Ungemach,   Ems,   Kissingen,   Nauheim,   Selters, 
Vichy,  Wildbad,  Kochbrunnen  (Wiesbaden),  Durkheim. 

(3)  In  beet-root,  many  samples  of  tobacco,  some  coffee 
and  tea,   ash  of  oak  and  beech,   crude  cream  of  tartar, 
potashes,  and  mother-liquor  from  the  Stassfurt  potassium 
salt  works. 

Extraction.  Rubidium  may  be  extracted  with  caesium 
from  lepidolite  (vid.  Extraction  of  Caesium). 

The  Element.  A.  Preparation.  Elementary  rubidium 
may  be  obtained  (i)  by  heating  the  charred  tartrates^to  a 
white  heat  (Bunsen) ;  (2)  by  reducing  the  hydroxide  or  the 
carbonate  with  magnesium  (Winkler,  Ber.  Dtsch.  diem. 
Ges.  xxui,  51) ;  (3)  by  reducing  the  hydroxide  with  alumi- 
num (Beketoff). 

B.  Properties.  Rubidium  is  a  soft  white  metal  which 
melts  at  38°  C.  It  takes  fire  in  the  air,  burning  to  the  oxide. 
It  decomposes  water.  Its  specific  gravity  is  1.52. 

Compounds.      A.    Typical   forms.       The  following  are 
typical  compounds  of  rubidium: 
Oxide,  Rb2O. 
Hydroxide,  RbOH. 
Carbonates,   Rb2CO3;  RbHCO3. 
Chloride,  RbCl. 
Double     chlorides,      HgCl2  •  2RbCl ;     HgCl2  -  2RbCl  +  2H2O ; 

2HgCl2  -  RbCl ;  4HgCl2  •  RbCl ;  PbCl4  •  2RbCl ;  2PbCl2  -  RbCl ; 

PbCl2  •  2RbCl  +  o.  sH2O ;      BiCl3  •  6RbCl ;      BiCl3  •  RbCl  + 

4H2O;     CdCl2-2RbCl;     2AsCl3.3RbCl;     3SbCl8-5RbCl; 

2SbCls  -  3RbCl ;         SbCl3  -  RbCl ;         2SbCl3  -  RbCl  +  H2O ; 

MnCV  2RbCl  +  2H2O ;  ZnCl2  •  2RbCl ;  MgCl2  •  RbCl  +  6H2O ; 

AuCl3  •  RbCl ;         TeCl4  •  2RbCl ;         T1C18  •  3RbCl  +  H2O ; 

TlCl3-2RbCl  +  H2O. 
Chlorate,  RbClO3. 
Perchlorate,  RbClO4. 
Bromides,  RbBr;  RbBr3. 


RUBIDIUM.  7 

Double  bromides,    2PbBr2-RbBr;   PbBr2-2RbBr  +  o.5H2O; 

2  AsBr3  •  3RbBr ;  2SbBr3  •  3RbBr ;  AuBr3  -  RbBr ; 

TeBr4-2RbBr;  TlBr3-3RbBr  +  H,O;  TlBr3-RbBr  +  H2O. 
Iodides,  Rbl ;  RbI3. 
Double  iodides,  AgI-2RbI;  PbI2-RbI  +  2H2O;  2AsI3-3RbI; 

2SbI3-3RbI;  TeI4-2RbI;  TlI3-RbI  +  2H2O. 
lodates,  RbIO3;  RbIO3-HIO3;  RbIO3-2HIO3. 
Nitride,  RbN3. 

Nitrates,  RbNO3;  3RbNO3-Co(NO3)3  +  H2O. 
Cyanide,  RbCN. 

Sulphates,  Rb2SO4;  RbHSO4;  Rb2S2O7;  Rb2Q.8SO3. 
Alums,          RbAl(SO4)2  +  i2H2O ;          RbFe(SO4)2  +  i2H2O ; 

RbCr(SO4)2+i2H2O;    Rb2SO4-Ti2O3-3SO3  +  24H2O. 
Chloroplatinate,  Rb2PtCl6. 
Silicofluoride,  Rb2SiF6. 

B.  Characteristics.  The  rubidium  compounds  are  very 
similar  to  those  of  potassium  and  caesium  (vid.  Caesium). 
Among  the  important  insoluble  salts  are  the  perchlorate 
(RbClO4),  the  silicofluoride  (Rb2SiF6),  the  chloroplati- 
nate  (Rb2PtCl6),  the  bitartrate  (RbHD2C4H4O4),  and  the 
alums  (RbAl(SO4)2  +  i2H2O  and  RbFe(S04)2+ i2H2O). 
The  salts  of  rubidium  color  the  flame  violet.  The  spec- 
trum gives  two  lines  in  the  violet  to  the  right  of  the  caesium 
lines  (Rba  and  Rb/?),  also  two  lines  not  so  distinct  in  the 
dark  red  (Rb?-  and  Rbd),  near  the  potassium  red  line,  at 
the  left  of  the  spectrum. 

Estimation  of  Caesium  and  Rubidium.  Caesium  and  ru- 
bidium may  be  estimated  in  general  by  the  methods 
applied  to  potassium.  They  are  usually  weighed  as  the 
normal  sulphates,  after  evaporation  of  suitable  salts  with 
sulphuric  acid  and  ignition  of  the  products ;  other  methods, 
however,  such  as  the  chloroplatinate  and  chloride  methods, 
are  possible.  They  may  also  be  weighed  with  a  fair  degree 
of  accuracy  as  the  acid  sulphates,  after  evaporation  with 
an  excess  of  sulphuric  acid,  and  heating  at  25o°-27o°  C. 


«  THE  RARER  ELEMENTS. 

until  a  constant  weight  is  obtained  (Browning,  Amer. 
Jour.  Sci.  [4]  xii,  301). 

Separation  of  Caesium  and  Rubidium.  These  metals  belong 
to  the  alkali  group.  From  sodium  and  lithium  they 
may  be  separated  (i)  by  chloroplatinic  acid,  with  which 
they  form  insoluble  salts;  and  (2)  by  aluminum  sulphate, 
with  which  they  form  difficultly  soluble  alums.  From 
potassium  they  may  be  separated  by  the  greater  solubility 
of  the  potassium  alum  and  chloroplatinate  in  water.* 

Caesium  and  rubidium  may  be  separated  from  each 
other  (i)  by  the  difference  in  solubility  of  the  chloroplati- 
nates;*  (2)  by  the  difference  in  solubility  of  the  alums;* 
(3)  by  the  formation  of  the  more  stable  and  less  soluble 
tartrate  of  rubidium;  and  (4)  by  the  solubility  of  caesium 
carbonate  in  absolute  alcohol.  Probably  the  most  satis- 
factory methods,  however,  are  those  suggested  by  Wells; 
they  depend  upon  the  insolubility  of  the  following  salts: 
caesium  double  chloride  and  iodide  (CsCl2I)  (Amer.  Jour. 
Sci.  [3]  XLIII,  17),  caesium-lead  chloride  (Cs2PbCl6)  (ibid. 
[3]  XLVI,  1 86),  and  caesium-antimony  chloride  (Cs2Sb2Cl9) 
(Amer.  Chem.  Jour,  xxvi,  265). 

EXPERIMENTAL  WORK   ON    CAESIUM  AND 
RUBIDIUM. 

Experiment  i.  Extraction  of  ccesium  and  rubidium  salts 
from  lepidolite.  Mix  thoroughly  in  a  lead  or  platinum 
dish  100  grm.  of  finely  ground  lepidolite  with  an  equal 
amount  of  powdered  fluorspar.  Add  50  cm.3  of  com- 
mon sulphuric  acid  and  stir  until  the  mass  has  the 
consistency  of  a  thin  paste.  Set  aside  in  a  draught  hood 
until  the  first  evolution  of  fumes  (SiF4  and  HF)  has  nearly 
ceased.  Heat  on  a  plate  or  sand-bath  at  a  temperature 
of  2Oo°-3oo°  C.  until  the  mass  is  dry  and  hard.  Pulverize 

*  Vid.  page  4. 


EXPERIMENTAL    WORK  ON  C/ESIUM  AND  RUBIDIUM.  9 

and  extract  with  hot  water  until  the  washings  give  no 
precipitate  on  the  addition  of  ammonium  hydroxide  to 
a  few  drops.  Evaporate  the  entire  solution  to  about 
100  cm.3  and  filter  while  hot  to  remove  the  calcium  sul- 
phate. Set  the  clear  filtrate  aside  to  crystallize.  The 
crystals,  consisting  of  a  mixture  of  potassium,  caesium, 
and  rubidium  alums,  with  some  lithium  salt,  should  be 
dissolved  in  about  100  cm.3  of  distilled  water,  and  allowed 
to  recrystallize.  This  process  of  recrystallization  should 
be  repeated  until  the  crystals  give  no  test  before  the  spec- 
troscope for  either  lithium  or  potassium.  The  amount  of 
caesium  and  rubidium  alums  obtained  will  of  course  vary 
with  the  variety  of  lepidolite  used.  An  average  amount 
of  the  mixed  alums  of  potassium,  caesium,  and  rubidium 
from  the  first  crystallization  would  be  10  grm.  The  pure 
caesium  and  rubidium  alums  finally  obtained  should  be 
about  3  grm.  (Robinson  and  Hutchins,  Amer.  Chem.  Jour, 
vi,  74).  Lithium  may  be  extracted  from  the  mother-liquor 
(vid.  Experiment  12). 

Experiment  2.  Preparation  of  ccesium  and  rubidium 
sulphates  (Cs2SO4;  Rb2SO4).  Dissolve  in  water  a  crystal 
of  the  caesium  and  rubidium  alums  obtained  from  lepido- 
lite, add  a  few  drops  of  ammonium  hydroxide,  and  boil. 
Filter  off  the  aluminum  hydroxide  and  evaporate  the 
filtrate  to  dryness.  Ignite  until  the  ammonium  sulphate 
is  removed,  dissolve  in  a  few  drops  of  water,  filter,  and 
evaporate  to  dryness.  Sulphates  of  caesium  and  rubidium 
will  remain. 

Experiment  3.  Preparation  of  the  carbonates  of  ccssium 
and  rubidium  (Cs2CO3 ;  Rb2CO3) .  Dissolve  in  water  a  crystal 
of  caesium  and  rubidium  alums  obtained  from  lepidolite, 
add  an  excess  of  barium  carbonate,  and  boil.  Filter  off 
the  alumina,  barium  sulphate,  and  excess  of  barium 
carbonate.  Pass  a  little  carbon  dioxide  through  the 
clear  filtrate  and  boil  to  remove  traces  of  barium  salt. 


io  THE  RARER  ELEMENTS. 

Filter.  Carbonates  of  caesium  and  rubidium  will  remain 
in  solution. 

Experiment  4.  Formation  of  the  double  chloride  of 
ccesium  and  tetravalent  lead  (2CsCl2-PbCl4).  To  a  few 
cm.3  of  a  one  per  cent,  solution  of  a  caesium  salt  add  a  few 
drops  of  the  reagent  obtained  by  warming  lead  dioxide 
with  hydrochloric  acid  and  allowing  the  solution  to  stand 
until  cool.  Make  a  similar  experiment,  using  a  rubidium 
salt  in  place  of  the  caesium  salt.  Note  the  absence  of  pre- 
cipitation in  this  case. 

Experiment  5.  Precipitation  of  the  double  chloride  of 
caesium  and  antimony  (3CsCl-2SbCl3).  To  a  few  cm.3  of 
a  one  per  cent,  solution  of  a  caesium  salt  add  some  anti- 
mony trichloride  in  solution  and  evaporate  to  a  small 
volume.  The  double  chloride  will  be  precipitated  on  cool- 
ing. Repeat  the  experiment,  using  a  rubidium  salt.  Note 
the  absence  of  precipitation  in  this  case. 

Experiment  6.  Precipitation  of  the  double  salt  ccesium 
chloride  and  stannic  chloride  (2CsCl-SnCl4).  Make  an  ex- 
periment similar  to  Experiment  5,  using  stannic  chloride 
in  the  place  of  antimonious  chloride.  Note  the  separa- 
tion of  the  double  chloride  on  cooling.  Make  a  similar 
experiment,  using  a  rubidium  salt. 

Experiment  7.  Precipitation  of  the  chloroplatinates  of 
ccesium  and  rubidium  (Cs2PtCl6;  Rb2PtCl6).  To  a  few 
cm.3  of  a  solution  of  a  caesium  salt  add  a  few  drops  of  a 
solution  of  chloroplatinic  acid.  Make  a  similar  experiment 
with  a  solution  of  a  rubidium  salt. 

Experiment  8.  Separation  of  ccesium  from  rubidium. 
Apply  the  information  gained  in  the  foregoing  experi- 
ments to  the  separation  of  caesium  from  rubidium. 

Experiment  9.  Flame  tests  for  ccesium  and  rubidium. 
Dip  the  end  of  a  platinum  wire  into  a  solution  of  a  caesium 
salt  and  test  the  action  of  the  flame  of  a  Bunsen  burner 
upon  it.  Repeat,  using  a  rubidium  salt. 


LITHIUM.  1 1 

Experiment  10.  Spectroscopic  tests  for  ccesium  and 
rubidium.  Test  solutions  of  caesium  and  rubidium  salts 
before  the  spectroscope.  Note  the  twin  blue  lines  of  the 
caesium  spectrum  and  the  twin  violet  lines  of  the  rubidium. 

Experiment  n.  Negative  tests  of  ccesium  and  rubidium. 
Note  that  hydrogen  sulphide,  ammonium  sulphide,  and 
ammonium  carbonate  give  no  precipitates  with  salts  of 
caesium  and  rubidium. 


LITHIUM,  Li,   7.03. 

Discovery.  In  1817  Arfvedson,  working  in  Berzelius's 
laboratory  upon  a  petalite  from  Uto,  Sweden,  discovered 
an  alkali  which  he  found  to  differ  from  those  already  known 
in  the  following  particulars:  (i)  in  the  low  fusing  points 
of  the  chloride  and  sulphate;  (2)  in  the  hydroscopic  char- 
acter of  the  chloride ;  and  (3)  in  the  insolubility  of  the  car- 
bonate. In  his  analysis  of  the  mineral  it  had  remained 
associated  with  sodium,  not  being  precipitated  by  tartaric 
acid.  To  the  newly  discovered  element  the  name  Lithium 
was  given,  from  Az'0o£,  stone,  because  it  differed  from 
sodium  and  potassium  in  having  a  mineral  rather  than 
a  vegetable  origin  (Ann.  der  Phys.  u.  Chem.  (1818),  xxix, 
229 ;  Ann.  Chim.  Phys.  [2]  x,  82).  It  has  since  been  found, 
however,  not  only  in  the  mineral  kingdom,  but  in  the 
vegetable  and  animal  kingdoms  also. 

Occurrence.     Lithium  is  found  combined  as  follows: 

(i)  In  minerals: 

Petalite,         LiAl(Si2O5)2,  contains  2-5%  Li2O. 

Spodumene,  LiAl(SiO3)2,  "         4-8%     " 

Lepidolite,     R3Al(SiOs)3,  "        4-6%     " 

Zinnwaldite,(K,Li)3FeAl3Si5016(OH,F)2,      "        3-4%     «• 
Cryophyllite,  complex  silicates,  vid.  Zinnwaldite,  contains. 
4-5%  Li.0. 


12  THE  RARER  ELEMENTS. 

Polylithionite,  complex  silicates,  vid.  Zinnwaldite,  contains 

about  9%  Li2O. 

Beryl,  Be^^SiC^,      contains  0-1%    Li2O. 

Triphylite,       Li(Fe,Mn)PO4,         "         8-9%      " 
Litkiophilite,  Li(Mn,Fe)P04,  8-9%     " 

Amblygonite,  Li(AlF)PO4,  "         8-10%    " 

Small  amotints  of  lithium  are  found  also  in  some  varie- 
ties of  tourmaline,  in  epidote,  muscovite,  orthoclase,  and 
psilomelane. 

(2)  In  certain  mineral  waters,  among  which  are  Durk- 
heim,    Kissingen,    Baden-Baden,    Bilin,    Assmannshausen, 
Tarasp,  Kreuznach,  Salzschlirf,  Aachen,  Selters,  Wildbad, 
Ems,    Homburg,    Karlsbad,    Marienbad,    Egger-Franzen- 
bad,    Wheal  Clifford. 

(3)  In    seaweed,    tobacco,    cacao,    coffee,    and   sugar- 
cane ;  in  milk,  human  blood,  and  muscular  tissue ;  in  me- 
teorites.    It  has  been  detected  also  in  the  atmosphere  of 
the  sun. 

Extraction.  Lithium  may  be  extracted  from  minerals 
by  the  following  methods: 

(i)  From  triphylite  or  lithiophilite.  The  coarsely  ground 
mineral  is  dissolved  in  Jiydrochloric  acid  to  which  nitric 
acid  is  gradually  added,  and  the  solution  obtained  is  treated 
with  a  sufficient  amount  of  ferric  chloride  to  unite  with  all 
the  phosphoric  acid  present.  This  solution  is  evaporated 
to  dryness  and  the  residue  is  extracted  with  hot  water. 
The  extract  thus  obtained  is  treated  with  barium  sulphide, 
to  remove  the  manganese  and  the  last  traces  of  iron.  The 
barium  is  removed  by  sulphuric  acid,  and  the  filtrate  is 
evaporated  with  oxalic  acid  and  ignited.  The  alkalies 
remain  as  carbonates  (Muller). 

Lithium  may  be  separated  from  the  other  alkalies  by 
treajj^the  mixed  carbonates  with  water,  lithium  carbonate 
b^il^cQrnparatively  insoluble. 
*          (2)  Prom  lepidolite  (or  any  other  silicate).     The  mineral  is 


LITHIUM.  1 3 

melted  at  red  heat  in  a  crucible,  the  melted  mass  is  cooled 
rapidly  in  water  and  pulverized.  Sufficient  water  is  added 
to  give  the  material  the  consistency  of  paste.  Hydrochloric 
acid  of  specific  gravity  1.2,  equal  in  weight  to  the  weight 
of  the  mineral  taken,  is  gradually  added,  with  stirring. 
The  mass  is  allowed  to  stand  for  twenty-four  hours.  It  is 
then  heated  again  to  about  100°  C.,  with  stirring,  and  a 
second  portion  of  acid  equal  to  the  first  is  added.  Upon 
several  hours'  heating  the  silica  separates  in  the  form  of 
powder,  and  after  treatment  with  nitric  acid  to  oxidize 
the  iron,  the  soluble  material  is  separated  by  filtration  from 
the  silica.  The  filtrate  is  heated  to  the  boiling-point  and 
treated  with  sodium  carbonate,  which  precipitates  iron, 
aluminum,  calcium,  magnesium,  manganese,  etc.  These 
are  removed  by  filtration,  and  the  liquid  is  evaporated  to 
a  small  volume  and  filtered  again  if  necessary.  Lithium 
carbonate  is  precipitated  by  more  sodium  carbonate 
(Schrotter). 

The  Element.  A.  Preparation.  Elementary  lithium 
may  be  obtained  by  subjecting  the  fused  chloride  to  elec- 
trolysis. Because  of  its  volatility  it  cannot,  like  sodium 
and  potassium,  be  prepared  by  heating  the  carbonate. 

B.  Properties.  Lithium  is  a  metallic  element  which  has 
a  silvery-white  luster  and  which  oxidizes  in  the  air,  though 
more  slowly  than  potassium  and  sodium.  It  decomposes 
water  at  ordinary  temperatures,  and  is  light  enough  to 
float  in  petroleum.  Its  melting-point  is  180°  C. ;  its  specific 
gravity  is  0.59. 

Compounds.  A.  Typical  forms.  The  following  are 
typical  compounds  of  lithium: 

Oxide,  Li2O. 

Hydroxide,  LiOH. 

Carbonate,  Li2COs. 

Chloride,  LiCl. 

Chlorate,  LiC108  +  o.5H2O. 


14  THE  RARER  ELEMENTS. 


Perchlorate, 

Bromide,  LiBr. 

Bromate,  LiBrO3. 

Iodide,  LiI  +  sH2O. 

lodate,  LiIO3  +  o.5H2O. 

Periodate,  LiIO4. 

Fluorides,  LiF;  LiF-HF. 

Nitride,  LiN3. 

Nitrite,   LiNO2  +  o.5H2O. 

Nitrate,  LiNO3. 

Sulphide,  Li2S. 

Sulphite,  Li2SO3. 

Sulphates,  Li2SO4;  KLiSO4;  NaLiS04;  etc. 

Phosphates,  LiH2PO4;  Li3PO4  +  o.5H20;  Li4P2O7. 

Carbide,  Li2C2. 

Silicofluoride,  Li2SiF6  +  2H2O. 

B.  Characteristics.  Most  of  the  salts  of  lithium  are 
easily  soluble  in  water;  the  principal  exceptions  are  the 
carbonate  and  the  phosphate,  which  are  difficultly  soluble. 
Lithium  resembles  sodium  more  closely  than  it  resembles 
the  other  alkalies,  in  that  it  does  not  form  an  insoluble 
chloroplatinate,  nor  a  series  of  alums.  The  nitrate  and 
the  chloride  are  soluble  in  alcohol.  The  compounds  of 
lithium  color  the  flame  brilliant  crimson. 

Estimation.  Lithium  is  usually  weighed  as  the  sul- 
phate or  chloride. 

Separation.  Lithium  may  be  separated  from  the  other 
members  of  the  alkali  group  (i)  by  the  ready  solubility  of  its 
chloride  in  amyl  alcohol  (Gooch,  Amer.  Chem.  Jour,  ix,  33)  ; 
(2)  by  the  solvent  action  of  absolute  ethyl  alcohol  upon 
the  chloride;  (3)  by  the  insolubility  of  the  phosphate; 
and  (4)  by  the  comparative  insolubility  of  the  carbonate. 


EXPERIMENTAL   WORK  ON  LITHIUM.  15 

EXPERIMENTAL  WORK  ON  LITHIUM. 

Experiment  12.  Extraction  of  lithium  salts  from  tri- 
-phylite  or  lithiophilite.  Dissolve  25  to  50  grm.  of  finely 
powdered  mineral  in  common  hydrochloric  acid,  add 
sufficient  nitric  acid  to  oxidize  the  iron,  and  enough  ferric 
chloride  to  combine  with  all  the  phosphoric  acid  present. 
Evaporate  to  dryness  and  extract  with  hot  water.  Treat 
the  extract  with  barium  hydroxide  in  slight  excess.  Filter, 
add  sulphuric  acid  to  complete  precipitation  of  barium 
sulphate,  and  filter  again.  Convert  the  sulphates  present 
into  carbonates  by  the  careful  addition  of  barium  carbonate, 
filter,  acidify  the  filtrate  with  hydrochloric  acid,  evaporate 
to  dryness,  and  extract  the  lithium  chloride  with  alcohol. 

(Lithium  salts  may  be  extracted  also  from  the  mother- 
liquor  after  the  extraction  of  caesium  and  rubidium  salts 
from  lepidolite.  The  liquor  is  treated  with  barium  car- 
bonate in  excess  and  is  then  boiled  and  filtered.  The 
filtrate  is  acidified  with  hydrochloric  acid,  evaporated  to 
dryness,  and  extracted  with  alcohol.) 

Experiment  13.  Precipitation  of  lithium  phosphate 
(Li3PO4) .  To  a  solution  of  a  lithium  salt  add  sodium  phos- 
phate in  solution. 

Experiment  14.  Precipitation  of  lithium  carbonate 
(Li2CO3).  To  a  few  drops  of  a  concentrated  solution  of  a 
lithium  salt  add  sodium  carbonate  in  solution. 

Experiment  15.  Solvent  action  of  alcohol  upon  lithium 
salts.  Try  the  action  of  ethyl  or  amyl  alcohol  upon  a  little 
dry  lithium  nitrate  or  chloride. 

Experiment  16.  Flame  and  spectroscopic  tests  for  lithium, 
(a)  Dip  a  platinum  wire  into  a  solution  of  a  lithium  salt 
and  hold  in  a  Bunsen  flame.  Note  the  color. 

(6)  Observe  the  lithium  flame  by  means  of  the  spectro- 
scope. Note  the  bright  crimson  line  between  the  potas- 
sium and  sodium  lines. 


1 6  THE  R/4RER  ELEMENTS. 

Experiment  17.  Negative  tests  of  lithium  salts.  Note 
that  hydrogen  sulphide,  ammonium  hydroxide,  ammonium 
carbonate  acting  upon  dilute  solutions,  and  chloroplatinic 
acid  give  no  precipitate  with  lithium  salts. 

BERYLLIUM  OR  GLUCINUM,  Be  or  Gl,  9.1. 
Discovery.  In  the  year  1797,  Vauquelin  discovered  beryl- 
lium or  glucinum  in  the  mineral  beryl  (Ann.  de  Chim.  xxvi, 
155).  After  having  removed  the  silica  in  the  usual  manner, 
he  precipitated  with  carbonate  of  potassium,  and  treated  the 
precipitate  with  a  solution  of  caustic  potash.  The  greater 
part  of  the  precipitate  dissolved,  leaving  a  residue  which  he 
found  to  consist  of  a  small  amount  of  iron  oxide  and  an 
oxide  which  dissolved  in  sulphuric  acid.  This  solution  gave, 
on  evaporation,  irregular  crystals  having  a  sweetish  taste 
and  forming  no  alum  with  potassium  sulphate.  The  sweet 
taste  suggested  for  the  new  element  present  the  name  Glu- 
cinum, from  yhvKvt,  sweet.  Recently  the  name  Beryllium, 
from  the  chief  source,  beryl,  has  come  into  more  general  use. 

Occurrence.     Beryllium  occurs  in  minerals  as  follows : 

Beryl,  Be3Al2(SiO3)6,         contains  u-i5%BeO. 

Chrysoberyl,  BeAl2O4,  19-20%    " 

Bertrandite,  Be2(Be-OH)2Si2O7,      "        40-43%    '•' 

Phenacite,  Be2SiO4,  44-46%    " 

Leucophanite,  Na(BeF)Ca(SiO3)2,      "        10-12%    " 

Meliphanite,  NaCa2Be2FSi3O10         "        10-14%    " 

Epididymite,  HNaBeSi3O8,  "        10-11%    " 

Enclose,  Be(Al-OH)SiO4,  17-18%    " 

Helvite  or  danalite,   R5(R2S)(SiO4)3,  "        13-14%     " 

Gadolinite,  FeBe2Y2Si2O10,  5~n%    " 

Trimerite,  Be(Mn,Ca,Fe)SiO4,      "         16-17%    " 

Beryllionite,  NaBePO4,  *'        19-20%    " 

Herderite,  Ca(Be(OH,F))PO4,     "        15-16%    " 

Hambergite,  Be(BeOH)BO3,  "        53~54%    4< 


BERYLLIUM  OR   GLUCINUM.  17 

Extraction.     Beryllium  is  generally  extracted  from  beryl 
by  one  of  the  following  methods : 

(1)  The  mineral  is  fused  with  sodium  and  potassium 
carbonates  (vid.  Experiment  18). 

(2)  The  finely  ground  mineral  is  fused  with  three  times 
its  weight  of  potassium  fluoride.     The  fused  mass  is  treated 
with  strong  sulphuric  acid  and  warmed;  by  this  process 
the  silica  is  removed  as  silicon  fluoride,  and  the  alumina 
and  potash  are  united  to  form  the  alum,  which  may  be 
crystallized  out  on  evaporation.     The  beryllium  remains 
in  solution  as  the  sulphate,  and  may  be  removed  by  treat- 
ment  with    ammonium   carbonate    (vid.    Experiments    18 
and  20). 

(3)  The  mineral  is  fused  with  calcium  fluoride.     This 
process  is  in  general  the  same  as  the  one  indicated  in  the 
second  method,   except  that  calcium  sulphate  is  formed 
and  must  be  removed  (Lebeau,  Chem.  News  LXXIII,  3). 

The  Element.  A.  Preparation.  Elementary  beryllium 
may  be  obtained  (i)  by  bringing  together  the  vapor  of 
the  chloride  and  sodium  in  a  current  of  hydrogen  (De- 
bray,  Ann.  Chim.  Phys.  (1855)  XLIV,  5);  (2)  by  fusing  the 
chloride  with  potassium  (Wohler,  Pogg.  Annal.  xiu,  577); 
(3)  by  heating  the  chloride  in  a  closed  iron  crucible  with 
sodium  (Nilson  and  Pettersson,  Ber.  Dtsch.  chem.  Ges.  xi, 
381,  906);  (4)  by  heating  the  oxide  with  magnesium 
(Winkler,  Ber.  Dtsch.  chem.  Ges.  xxm,  120). 

B.  Properties.  The  element  beryllium  is  grayish  to 
white  in  color.  Unchanged  in  the  air  at  ordinary  tem- 
peratures, it  burns  brightly  to  the  oxide  when  heated  in 
air  or  in  oxygen.  It  does  not  decompose  hot  or  cold  water. 
Heated  in  sulphur  vapor  it  forms  the  sulphide,  and  in 
chlorine  the  chloride.  It  is  soluble  in  dilute  and  in  con- 
centrated acids;  also  in  potassium  hydroxide  with  the 
liberation  of  hydrogen.  Determinations  of  its  specific 
gravity  range  from  1.64  to  2.1. 


1 8  THE  R4RER  ELEMENTS. 

Compounds.     A.   Typical    forms.      The    following    are 
typical  compounds  of  beryllium: 
Oxide,   BeO. 
Hydroxide,   Be(OH)2. 

Carbonates,  BeCO3+4H2O;  #BeCO3-;yBeO. 
Chlorides,    BeCl2;   BeCl2  +  4H2O;  *BeCl2-;yBe(OH)2  +  0H2O. 
Chlorate,  Be(ClO4)2  +  4H2O. 
Bromides,  BeBr2;  BeBr2  +  4H2O. 
Iodide,  BeI2. 

Fluorides,  BeF2;  BeF2-KF;  BeF2-2KF. 
Nitrates,      Be(NO3)2  +  3H2O;      Be(NO3)2-Be(OH)2-f  2H2O; 

Be(NO3)2-2BeO. 

Sulphates,  BeSO4;  BeSO4  +  4H2O;  BeSO4  +  7H2O. 
Sulphites,  BeSO3;  BeSO3-BeO;  3BeSO3-BeO. 
Phosphate,  Be3(PO4)2  +  6H2O. 
Ferrocyanides,   Be2FeC6N6;   Be2Fe(CN)6-4Be(OH)2. 

B.  Characteristics.  The  compounds  of  beryllium  closely 
resemble  those  of  aluminum.  The  oxide  is  white,  in- 
soluble in  water,  and  when  freshly  precipitated  soluble 
in  excess  of  potassium  hydroxide.  If  this  solution  is  di- 
luted and  boiled,  the  oxide  is  reprecipitated ;  in  this  reaction 
beryllium  differs  from  aluminum.  The  salts  of  beryllium 
with  the  stronger  acids  (hydrochloric,  nitric,  and  sulphuric) 
are  soluble,  like  the  corresponding  salts  of  aluminum.  The 
sulphate  of  beryllium  does  not  unite  with  potassium  sul- 
phate to  form  an  alum.  Ammonium  carbonate  precipi- 
tates the  basic  carbonates  of  both  aluminum  and  beryl- 
lium, but  the  beryllium  carbonate  is  very  soluble  in  excess 
and  may  be  reprecipitated  by  boiling. 

Estimation.  Beryllium  is  ordinarily  estimated  as  the 
oxide,  (BeO),  which  is  obtained  by  the  ignition  of  the  pre- 
cipitated hydroxide. 

Separation.  Beryllium  falls  into  the  aluminum  group, 
and  it  closely  resembles  that  element  in  many  reactions. 
It  may  be  separated  from  aluminum  (i)  by  boiling  a  dilute 


, 


EXPERIMENTAL   WORK  ON  BERYLLIUM.  19 

solution  of  the  two  hydroxides  in  sodium  or  potassium 
hydroxide,  beryllium  hydroxide  being  precipitated;  (2) 
by  precipitating  the  basic  acetate  of  aluminum,  the  beryl- 
lium salt  remaining  in  solution;  and  (3)  by  saturating  a 
solution  of  the  two  chlorides  with  hydrochloric  acid  gas 
in  the  presence  of  ether,  the  beryllium  remaining  in  solu- 
tion, while  the  aluminum  chloride  is  precipitated  (Gooch 
and  Havens,  Amer.  Jour.  Sci.  [4]  n,  416). 

EXPERIMENTAL  WORK  ON   BERYLLIUM. 

Experiment  18.  Extraction  of  beryllium  salts  from 
beryl  (Be^l^O^).  Fuse  in  a  clay  crucible  10  grm.  of 
finely  powdered  mineral  with  20  grm.  of  a  mixture  of  sodium 
and  potassium  carbonates,  and  cool.  Pour  about  20  cm.3 
of  common  sj^huric_acid  over  the  fused  mass  and  stir 
0»o  until  it  becomes  gelatinous.  Heat  until  the  excess  of  sul- 
phuric acid  is  driven  off  and  extract  with  water.  Evapo- 
rate to  about  100  cm.3,  filter  if  necessary,  and  allow  the 
potash  alum  to  crystallize  out.  After  removing  the  alum, 
saturate  the  filtrate  with  ammonium  carbonate  in  the  cold, 
allow  it  to  stand  for  several  hours,  and  filter.  Boil  the 
filtrate  and  collect  the  basic  beryllium  carbonate  precipi- 
tated (#BeCO3  •  ;yBeO) .  To  purify  this  salt  from  iron,  dis- 
solve it  in  a  small  amount  of  acid,  add  potassium  hydroxide 
in  excess,  filter  off  the  ferric  hydroxide  precipitated,  dilute 
the  filtrate,  and  boil. 

Experiment  19.  Precipitation  of  beryllium  hydroxide 
(Be(OH)2).  (a)  To  a  solution  of  a  beryllium  salt  add 
ammonium  hydroxide,  and  note  the  insolubility  of  the 
precipitate  in  excess  of  that  reagent. 

(6)  To  another  portion  of  the  beryllium  solution  add 
a  solution  of  potassium  or  sodium  hydroxide,  and  note 
the  solvent  action  of  an  excess. 

(c)  Dilute  with  water  a  portion  of  the  alkaline  solution 


20  THE  RARER  ELEMENTS. 

obtained  in  (b)  and  boil.      Note  the  reprecipitation  of  the 
hydroxide. 

(d)  To   another  portion   of   the   alkaline    solution   ob- 
tained in  (6)  add  ammonium  chloride,  and  boil. 

(e)  To  a  solution  of  a  beryllium  salt  add  ammonium 
sulphide. 

Experiment  20.  Precipitation  of  beryllium  carbonate 
(#BeCO3-;yBeO).  (a)  To  a  solution  of  a  beryllium  salt  add 
sodium  or  potassium  carbonate  in  solution.  Note  the 
solvent  action  of  an  excess  and  the  reprecipitation  on 
boiling. 

(b)  Make  a  similar  experiment,  using  ammonium  car- 
bonate. 

Experiment  21.  Precipitation  of  beryllium  phosphate 
(Be3(PO4)2).  To  a  solution  of  a  beryllium  salt  add  a  solu- 
tion of  sodium  phosphate. 

Experiment  22.  Precipitation  of  beryllium  ferrocyanide 
(Be2Fe  (CN)  6  •  466  (OH)  2) .  To  a  solution  of  a  beryllium  salt 
add  a  little  potassium  ferrocyanide  in  solution. 

Experiment  23.  Negative  tests  of  beryllium  salts.  Try 
the  action  of  hydrogen  sulphide  and  ammonium  oxalate 
upon  separate  portions  of  a  solution  of  a  beryllium  salt. 
Add  sodium  acetate  to  a  solution  of  a  beryllium  salt  and 
boil.  Note  the  absence  of  precipitation  in  each  case. 

YTTRIUM,  Y,   89. 

Discovery.  In  the  year  1794  Gadolin  (Kongl.  Vet. 
Acad.  Handl.  xv,  137;  Crell  Annal.  (1796)  i,  313)  discov- 
ered a  new  earth  *  in  a  mineral  from  Ytterby  later1  called 
Gadolinite,  which  had  been  discovered  by  Arrhenius  and 
described  by  Geyer  in  1788  (Crell  Annal.  (1788)  i,  229). 

*  The  term  earth  is  applied  to  certain  metallic  oxides  which  were  formerly 
regarded  as  elementary  bodies,  as  Y2O3,  Er2O3,  La2Os,  etc.,  and  names  ending 
in  a  are  often  used  in  designating  them,  as  yttria,  erbia,  etc.  The  ending 
um  designates  the  element,  as  yttrium,  erbium,  lanthanum. 


YTTRIUM.  21 

In  1797  Eckeberg  confirmed  Gadolin's  discovery  and  named 
the  new  earth  Yttria  (Kong.  Vet.  Acad.  Handl.  xvm,  156; 
Crell  Annal.  (1799)  n,  63). 

Occurrence.  Yttrium  occurs  always  in  combination. 
Yttrium  earths,  chiefly  Y2O3,  are  found  as  shown  in  the 
following  table: 

Gadolinite,  FeBe2Y2Si2O10 22-46% 

in 

Yttrialite,  R2O3-2SiO2 46-47% 

Cappelenite,  complex  silicates  .  . 52~53% 

Melanocerite,      "                        9~io% 

Caryocerite,        "              "         2-3% 

Tritomite,           "              "        2-3% 

ii  in 

Allanite  or  orthite,  HRR3Si3O13 0-4% 

Cenosite,  H4Ca2(Y,Er)2CSi4O17 - 37~38% 

Thalenite,    H2Y4Si4O15 58-63% 

Rowlandite,  *Y2O3  -^SiO2 61-62% 

Bodenite,       vid.  Allanite 17-18% 

Muromonite,  "          "       37-38% 

Keilhauite,  complex  silicates. 6-7% 

Tscheffkinite,     "                           0-3% 

Johnstrupite,      ' '                           i-  2% 

Mosandrite,                                    o-  3% 

Rinkite,               "           "             o-  i% 

Xenotime,  YPO4 54-64% 

Monazite,  (Ce,La,Di)PO4 0-5% 

Rhabdophanite,  RPO4 -H2O 2-10% 

in 

Yttrocerite,  2(2RF3-9CaF2)  -3H20 14-15% 

Fluocerite,  R2O3-4RF3 3-4% 

ii   in 

Samarskite,  R3R2(Nb,Ta)6O21 12-16% 

in  in 

Euxenite,  R(NbO3)3  -R2(TiO3)3  -|H2O ' . . .  .  13-30% 

in 

Fergusonite,  R(Nb,Ta)O4 30-46% 

ii  in 

Yttrotantalite,  RR2(Ta,Nb)4015-4H20 17-20% 


22  THE  RARER  ELEMENTS. 

Hatchettolite,  R(Nb,Ta)2O6-H20 0-2% 

o 

Annerodite,  complex  niobate 7-  8% 

Hielmite,  complex  stanno-tantalate J~  5% 

in                in 
^schynite,  R2Nb4O13  .R2(Ti,Th)5O13 1-3% 

Polymignite,  SRTiO3 •  SRZrO3 -R(Nb,  Ta)2O6 2-  3% 

III  III 

Polycrase,  R(NbO3)3  •  2R(TiO3)3  •  sH2O 20-32% 

Arrhenite,  complex  tantalo-niobate 22-23% 

Rogersite,       "  '"  " 60-61% 

Sipylite,  complex  niobate,  Er2O3.  .  .27%;  Y2O3.  .  .  i% 

Extraction.  The  following  are  common  methods  for  the 
extraction  of  yttrium  salts  from  minerals: 

(1)  From  gadolinite  (or  any  other  silicate).     The  finely 
powdered  mineral  is  mixed  with  common  sulphuric  acid  until 
the  mass  has  the  consistency  of  thick  paste.      It  is  then 
heated  until  dry  and  hard,  pulverized,  and  extracted  with 
cold  water.     From  this  extraction  the  oxalates  are  precipi- 
tated by  the  addition  of  oxalic  acid ;  they  are  then  washed, 
dried,  and  heated  at  400°  C.     The  oxides  thus  obtained  are 
dissolved  in  sulphuric  acid,  and  the  solution  is  saturated  with 
potassium  or  sodium  sulphate.     The  double  sulphates  of 
the  cerium  group  are  precipitated,  and  the  members  of  the 
yttrium  group  remain  in  solution. 

(2)  From  gadolinite.     The   mineral  is  decomposed  by 
aqua  regia  (vid.  Experiment  24). 

(3)  From  samarskite.     The  mineral  is  decomposed  by 
hydrofluoric  acid.     The  niobic  and  tantalic  acids  go  into 
solution,  and  the  yttrium  earths,  together  with  uranium 
oxide,     remain     (Lawrence    Smith,    Amer.    Chem.    Jour. 

v,  44). 

The  Element.  A.  Preparation.  Elementary  yttrium 
may  be  obtained  (i)  by  heating  the  chloride  with  potas- 
sium (Berzelius) ;  (2)  by  subjecting  the  melted  double 


YTTRIUM.  23 

chloride  of  sodium  and  yttrium  to  electrolysis  (Cleve,  Bull. 
Soc.  Chim.  d.  Paris  [2]  xvm,  193) ;  (3)  by  heating  the 
oxide  with  magnesium  (Winkler,  Ber.  Dtsch.  chem.  Ges. 
xxm,  787). 

B.  Properties.  Yttrium  is  a  grayish-black  powder, 
which  decomposes  water  only  slightly  at  ordinary  tempera- 
tures, but  more  rapidly  on  boiling,  forming  the  oxide. 
Ignited  on  platinum  in  the  air,  it  burns  to  the  oxide  with  a 
brilliant  light ;  in  oxygen  with  a  very  intense  glow.  It  is 
very  soluble  in  dilute  acids,  including  acetic,  but  is  only 
slightly  soluble  in  concentrated  sulphuric  acid.  It  decom- 
poses potassium  hydroxide  at  the  boiling  temperature. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  yttrium: 

Oxide,  Y2O3. 
Hydroxide,  Y(OH)3. 

Carbonates,  Y2(CO3)3  +  3H2O ;         Y2(CO3)3  - Na2CO3  +  4H2O ; 
Y2(C03)3-(NH4)2C03  +  2H20. 

Chlorides,    YC13;        YC13  +  6H2O;         YCl3.3HgCl2  +  9H2O; 

YC13  •  2AuCl3  +  i6H2O ;  2YC13-  3PtCl2+  24H2O. 

Chlorate,  Y(C1O3)3  +  8H2O. 
Perchlorate,  Y(C1O4)3  +  8H2O. 
Bromides,  YBr3;  YBr3  +  gH2O. 
Bromate,  Y(BrO3)3  +  9H2O. 
Iodide,  YI3. 

lodate,  Y(I03)3  +  3H20. 
Periodate,  Y2O3-I2O7  +  8H2O. 
Fluoride,  YF3  +  o.5H2O. 

Nitrates,  Y(N03)3  +  6H2O;  2Y2O3.3N2O5  +  9H2O. 
Cyanides,  YKFe(CN)fl  +  2H2O;  Y(SCN)3  +  6H2O. 
Sulphates,  Y2(S04)3  +  8H2O ;  Y2(SO4)8  -  4K2S04 ; 

Y2(S04)3.Na2C03  +  2H20. 
Sulphite,  Y2(S08)3  +  3H20. 


24  THE  RARER  ELEMENTS. 

Seleniates,  Y2(SeO4)3  +  8H2O ;         Y2(SeO4)3  •  K2SeO4  +  6H2O ; 

Y2(Se04)3.(NH4)2Se04  +  6H20. 
Selenites,  Y2(SeO3)3  +  1 2H2O ;  Y2O3  •  4SeO2  +  4H2O. 
Sulphide,  Y2S3. 
Oxalate,  Y2(C2O4)3  +  9H2O. 
Phosphates,  YPO4;  Y(PO3)3;  YHP2O7  +  3.5H2O. 
Chromate,  Y2(CrO4)3  -  K?CrO4  +  #H2O. 
Tungstate,  Y2(WO4)3  +  6H2O. 
Carbide,  YC2. 

B.  Characteristics.  The  compounds  of  yttrium  have 
few  characteristic  reactions.  They  resemble  quite  closely 
the  compounds  of  aluminum,  but  yttrium  differs  from 
aluminum  in  having  a  hydroxide  insoluble  in  excess  of 
sodium  or  potassium  hydroxide  and  in  forming  no  alums. 
The  salts  of  yttrium  give  no  absorption  spectra.  Yttrium 
sulphate  differs  from  the  sulphate  of  cerium  in  forming 
no  insoluble  double  sulphate  with  potassium  or  sodium 
sulphate. 

Estimation.  Yttrium  is  generally  weighed  as  the  oxide, 
(Y2O3),  which  has  been  obtained  by  the  ignition  of  the 
hydroxide  or  the  oxalate. 

Separation.  In  the  course  of  analysis  the  yttrium 
earths  are  precipitated  with  the  aluminum  group.  They 
may  be  separated  from  aluminum  by  precipitation  with 
oxalic  acid  or  ammonium  oxalate  in  faintly  acid  solution; 
in  this  reaction  they  resemble  the  other  members  of  the 
rare-earth  group  (Ce,  La,  Di,  Th,  Zr,  etc.).  They  may  be 
separated  from  these  by  saturating  a  solution  of  the  sul- 
phates with  potassium  sulphate;  the  yttrium  earths  do 
not  form  a  double  sulphate  insoluble  in  potassium  sulphate 
as  do  the  others. 

For  the  separation  of  yttrium  from  the  very  rare  mem- 
bers of  its  group  (Yb,  Er,  Tr,  etc.),  vid.  Dennis  and  Dales, 
Jour.  Amer.  Chem.  Soc.  xxiv,  401. 


EXPERIMENTAL   WORK  ON   YTTRIUM.  2 5 

* 

EXPERIMENTAL  WORK  ON  YTTRIUM. 

Experiment  24.  Extraction  of  yttrium  salts  from  gado- 
linite  (Be2FeY2Si2O10).  Warm  5  grm.  of  finely  powdered 
mineral  with  aqua  regia  until  it  is  completely  decomposed. 
Evaporate  on  a  water-bath  and  desiccate  to  remove  the 
silica.  Extract  with  hot  water  and  a  little  hydrochloric 
acid,  and  add  to  the  extract  ammonium  oxalate  until 
precipitation  ceases.  Filter  off  the  precipitate,  which  con- 
sists of  the  oxalates  of  the  yttrium  and  cerium  groups,  to- 
gether with  traces  of  the  oxalates  of  manganese  and  cal- 
cium; dry  and  ignite.  Dissolve  in  a  small  amount  of 
hydrochloric  acid  the  oxides  thus  obtained,  and  saturate 
the  solution  with  potassium  sulphate;  this  precipitates 
the  members  of  the  cerium  group  as  the  double  sulphates. 
Filter,  and  wash  with  a  solution  of  potassium  sulphate. 
From  the  filtrate  precipitate  the  yttrium  earths  by  an 
alkali  hydroxide  or  oxalate.  To  remove  the  manganese 
and  calcium,  dissolve  the  precipitate  in  nitric  acid,  evapo- 
rate to  dryness,  and  heat  until  the  manganese  salt  is  decom- 
posed. Extract  with  water,  filter  off  the  oxide  of  man- 
ganese, treat  the  filtrate  with  ammonium  hydroxide,  and 
stir  thoroughly.  The  calcium  hydroxide  will  be  dissolved, 
and  the  yttrium  earths  precipitated. 

Experiment  25.  Precipitation  of  yttrium  hydroxide 
(Y(OH)3).  (a)  To  a  solution  of  an  yttrium  salt  add  am- 
monium hydroxide. 

(6)  Repeat  the  experiment,  using  sodium  or  potassium 
hydroxide. 

Note  the  insolubility  in  excess  in  each  case. 

(c)  Precipitate  yttrium  hydroxide  by  the  action  of 
ammonium  sulphide. 

Experiment  26.  Precipitation  of  yttrium  carbonate 
(Y2(CO3)3).  (a)  To  a  solution  of  an  yttrium  salt  add 
ammonium  carbonate. 


26  THE  RARER  ELEMENTS. 

(b)  Repeat  the  experiment,  using  sodium  or  potassium 
carbonate. 

Note  the  solubility  in  the  cold  upon  the  addition  of  an 
excess  of  the  alkali  carbonates,  and  the  reprecipitation 
on  boiling. 

(c)  Try  the  action  of  the  common  acids  upon  yttrium 
carbonate. 

Experiment  27.  Precipitation  of  yttrium  oxalate 
(Y2(C2O4)3).  To  a  solution  of  an  yttrium  salt  add  a  solu- 
tion of  either  oxalic  acid  or  an  alkali  oxalate. 

Experiment  28.  Precipitation  of  yttrium  phosphates 
(Y2(HPO4)3;  YPO4).  To  a  solution  of  an  yttrium  salt 
add  sodium  phosphate  in  solution  (Na2HPO4).  The  pre- 
cipitate is  said  to  be  of  the  acid  form  Y2(HPO4)3.  The 
neutral  phosphate  (YPO4)  is  formed  by  treating  an  yttrium 
salt  in  solution  with  an  ammoniacal  phosphate. 

Experiment  29.  Precipitation  of  yttrium  ferrocyanide 
(YKFe(CN)6).  To  a  solution  of  an  yttrium  salt  add  potas- 
sium ferrocyanide. 

Experiment  30.  Precipitation  of  yttrium  chr  ornate 
(#Y2(CrO4)3-;yY2O3).  To  a  solution  of  an  yttrium  salt  add 
a  solution  of  potassium  chromate,  and  neutralize  if  necessary. 

Experiment  31.  Precipitation  of  yttrium  fluoride  (YF3). 
To  a  solution  of  an  yttrium  salt  add  potassium  fluoride. 

Experiment  32.  Negative  tests  of  yttrium  salts.  Note 
that  hydrogen  sulphide  gives  no  precipitate  with  yttrium 
salts,  and  that  saturation  of  a  solution  of  an  yttrium  salt 
with  potassium  or  sodium  sulphate  gives  no  insoluble 
double  salt. 

THE    GADOLINITE    OR   YTTRIUM    EARTHS 

OTHER    THAN   YTTRIA. 

Associated  with  yttria,  and  resembling  it  in  many 
reactions,  are  several  very  rare  earths  which,  together  with 
yttria,  comprise  the  group  called  the  Gadolinite  or  Yttrium 


THE   GADOLINITE   OR    YTTRIUM  EARTHS.  27 

Earths.     The   metals   of  these   very   rare   oxides   are  the 
following: 

!^>  IL 

Terbium,  Tfc  161-3  Samarium,  Sm,  150 

Erbium,  Er,  166  Decipium,  Dp,  171 

Holmium,  Ho,  162  Gadolinium,  Gd,  156 

Thulium,  Tm,  171 

Dysprosium,  Dy. 

Ytterbium,  Yb,  173 

Philippium,  Pp,  123-6 

Scandium,  Sc,  44 .  i 

The  elements  in  column  II  are  classed  by  some  authori- 
ties with  the  cerium  group. 

Discovery.*  In  1843  Mosander  (J.  pr.  Chem.  xxx,  288) 
announced,  as  the  result  of  his  investigation  of  yttria,  its 
separation  into  three  earths,  two  white  and  one  yellow. 
To  the  less  basic  of  the  white  oxides  he  gave  the  name 
Terbium  earth,  to  the  more  basic  the  original  name  Yttrium 
earth,  and  the  yellow  oxide  he  called  Erbium  earth. 

In  1878  Marignac  (Compt.  rend.  LXXXVII,  578)  found  in 
gadolinite  the  oxide  of  a  new  element  which  he  named  Ytter- 
bium, and  the  same  year  Delafontaine  (Compt.  rend.  LXXXVII, 
559,  632)  announced  the  isolation  from  a  North  Carolina 
samarskite  of  the  earths  of  Decipium  and  Philippium. 

The  following  year  Nilson  (Ber.  Dtsch.  chem.  Ges.  xn, 
554),  while  engaged  in  extracting  ytterbium  from  euxenite, 
separated  an  earth  of  much  lower  atomic  weight,  the 
unknown  element  of  which  he  called  Scandium.  Another 
earth  isolated  in  1879  is  the  oxide  of  Samarium,  discovered 
by  Lecoq  de  Boisbaudran  (Compt.  rend.  LXXXVIII,  323) 
in  the  course  of  an  examination  of  the  absorption  spectra 
of  the  earths  separated  from  samarskite. 

In  1880  Cleve  (Compt.  rend.  LXXXIX,  478),  while  work- 

*  For   a  recent   and  more  detailed  account  of   the  discovery  of   these 
earths  -vid.  Baskerville,  Science,  New  Series,  xvn,  774. 


28  THE  RARER  ELEMENTS. 

ing  on  erbium  earth,  discovered  two  elements,  Holmium 
and  Thulium,  which  he  separated  as  the  oxides. 

Six  years  later  Marignac  and  Lecoq  de  Boisbaudran 
(Compt.  rend,  en,  902),  during  the  study  of  terbium  earth, 
separated  the  oxide  of  an  unknown  element  named  by 
them  Gadolinium,  and  in  the  same  year  Lecoq  de  Bois- 
baudran (Compt.  rend,  en,  1004)  made  the  further  an- 
nouncement of  the  isolation  of  a  new  earth  from  the  oxide 
of  holmium,  that  of  Dysprosium. 

Occurrence.  These  earths  are  found  associated  with 
yttrium  in  small  quantities  and  varying  proportions  (vid. 
Occurrence  of  Yttrium). 

Extraction.*  Methods  for  the  extraction  of  the  yttrium 
earths  have  already  been  given  (vid.  Extraction  of  Yttrium). 
Methods  for  their  separation  are  as  follows: 

(1)  Fractional  precipitation  by  ammonium  hydroxide 
(Mosander) ; 

(2)  Fractional     precipitation     by     potassium    oxalate 
(Delafontaine) ; 

(3)  Successive  ignitions  of  the  nitrates,  and  extractions 
with  water  (Bahr  and  Bunsen) ; 

(4)  Precipitation  by  means  of  lactic  acid  (Waage) ; 

(5)  Treatment  with  ethylsulphate    (Urbain). 

The  Elements.  The  metallic  elements  of  these  earths 
have  not  been  isolated. 

Compounds.  A.  Typical  forms.  The  typical  com- 
pounds of  five  elements  of  the  yttrium  group  are  given  on 
the  next  page. 

B.  Characteristics.  The  existence  of  the  earths  of  er- 
bium, terbium,  ytterbium,  scandium,  and  samarium  has 

*  References:  Mosander  and  Delafontaine,  J.  pr.  Chem.  xciv,  297;  Bahr 
and  Bunsen,  Ann.  Chem.  Pharm.  cxxxvii,  i ;  Auer  v.  Welsbach,  Monatshefte  f. 
Chem.  iv,  630;  Waage,  Chem.  Ztg.  (1895),  1072;  Drossbach,  Ber.  Dtsch.  chenu 
Ges.  xxix,  2452;  Urbain,  Chem.  Ztg.  (1898),  271;  Dennis  and  Dales,  Jour. 
Amer.  Chem.  Soc.  xxiv,  401. 


THE  GADOL1NITE  OR    YTTRIUM  EARTHS. 


29 


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3°  THE  RARER  ELEMENTS. 

been  quite  definitely  established.  The  other  members  of 
the  gadolinite  group  are  still  more  or  less  in  doubt.  Of  the 
five  mentioned  above,  the  first  four  closely  resemble  yttrium. 
Solutions  of  terbium,  ytterbium,  and  scandium  salts  give 
no  absorption  spectra.  The  salts  of  erbium  are  of  a  rosy 
tint,  and  give  an  absorption  spectrum.  The  double  sul- 
phates of  these  four  elements  respectively  with  potassium 
sulphate  are  soluble  in  a  solution  of  potassium  sulphate, 
the  ytterbium  and  scandium  salts  being  more  soluble,  how- 
ever, than  those  of  erbium  and  terbium.  Samarium  re- 
sembles cerium.  Its  salts  are  yellowish,  and  the  solutions 
give  an  absorption  spectrum.  The  double  sulphate  with 
potassium  sulphate  is  insoluble  in  a  solution  of  potassium 
sulphate. 

CERIUM,  Ce,  140. 

Discovery.  In  the  course  of  the  analysis  of  a  mineral 
from  Riddarhyttan,  Sweden,  in  1803,  Klaproth  discovered 
an  earth  which,  while  resembling  yttria  in  many  of  its 
reactions,  differed  from  it  in  being  insoluble  in  carbonate 
of  ammonium,  and  in  acquiring,  when  ignited,  a  light  brown 
color.  Because  of  this  latter  peculiarity,  the  name  Ochroite 
suggested  itself  to  him,  from  'caXpoz,  yellow  brown  (Phil. 
Mag.  xix,  95).  At  the  same  time,  and  independently  of 
Klaproth,  Berzelius  and  Hisinger  made  the  same  discovery. 
Their  name  for  the  new  element  was  Cerium,  chosen  in  honor 
of  the  discovery  of  the  planet  Ceres  by  Piazzi  in  1801  (Phil. 
Mag.  xx,  155;  xxn,  193). 

Occurrence.  Cerium  is  found  in  many  minerals,  asso- 
ciated, usually,  with  lanthanum  and  didymium. 

Contains 
Ce,O,  Di2O3+La2CX 

Cerite,  (Ca,Fe)  (CeO)  (Ce2  •  3OH)  (SiO,),. .  24-65  %         7-35 % 

n  in 
Allanite  or  orihite,  HRR3Si3O13 1-18%         1-16% 

Gadolinite,  Be2FeY2Si2O10 1-10%         2-20% 


CERIUM.  31 

Contains 
Ce203 

Cappelenite,    complex  silicates 1-2%  2-  3% 

Melanocerite,                      "       20-2 1  %  20-2 1  % 

Caryocerite,                                 14-1 5  %  20-2 1  % 

Tritomite,                            M       19-21%  21-26% 

Tscheffkinite,       "      silico-titanates.  .  12-20%  17-20% 

Johnstrupite,        "           "          "              12-13%  * 

Mosandrite,          "           "         "              16-26%  * 

Rinkite,                 "           "          "             21-22%  * 
Mackintoshite, 

U02-3Th02.3Si02.3H20. . . .   45-46%t 

Monazite,  (Ce,  La,  Di)PO4 16-36%  20-24% 


Churchite,  R3P208-4H20 50 

Xenotime,  YPO4 0-11%           * 

Rhabdophanite,  RPO4  -H2O 23%             55% 

Fluocerite,  R2O2  -4RF3 39~46%       3o-36% 

Tysonite,  (Ce,  La,  Di)F3 40%             3o% 

in 

Yttrocerite,  (2RF3  •  9CaF2)  •  3H20 5  %               5 % 

Parisite,  (CaF) (CeF)Ce(CO3)3 38%             15% 

Bastnaesite, 

(Ce,  La,  Di)2C3Oe.(Ce,  La,  Di)F3.  .  28-41%       35~46% 

Lanthanite,  La2(CO3)3-9H20 52% 

Samarskite,  R3R2(Nb,Ta)6O21 2-5%           * 

IK 

Fergusonite,  R(Nb,Ta)O4 0-9%           * 

m  in 

Euxenite,  R(NbO3)3.R2(TiO3)3.|H2O.  2-  8% 

Zirkelite,  (Ca,Fe)O  •  2(Zr,  Ti,  Th)O2. .  .  2-  3% 

Polycrase,R(Nb03)3.2R(Ti03)3-3H20  2-  3% 
Polymignite, 

SRT^-sRZrO^^Nb.Ta)^.-.--  6%            5% 

III  III 

^Eschymte,  I^Nbp13-I^(Ti,Th)5O13. .  18%            5% 


*  Included  under  Ce2Os.  f  Ce2O3+  ThO2. 


32  THE  RARER  ELEMENTS. 

Contains 
Ce2O3 

Hielmite,  formula  doubtful 0.5-1% 

Annerodite,    "  "         . '. 2-3% 

ii  in 
Yttrotantalite,  RR2(Ta,Nb)4O15-4H2O.        o-  2% 

Sipylite,  complex niobate i%         8% 

Pyrochlore,  RNb2O6-R(Ti,Th)O3 5-  7% 

Arrhenite,  formula  doubtful 2~  3  %         * 

Extraction.  Cerium  is  generally  extracted  from  cerite 
through  decomposition  of  the  mineral  by  heating  it  with 
strong  sulphuric  acid  (vid.  Experiment  33).  The  decom- 
position may  be  accomplished  also  by  the  action  of  a  mix- 
ture of  strong  hydrochloric  and  nitric  acids,  but  better 
results  may  be  expected  by  the  former  method. 

The  Element.  A.  Preparation.  Elementary  cerium  may 
be  obtained  (i)  by  reducing  the  chloride  with  sodium  or 
potassium  (Mosander) ;  (2)  by  subjecting  the  double  chloride 
of  cerium  and  sodium  to  electrolysis  (Pogg.  Annal.  CLV,  633). 

B.  Properties.  In  appearance  cerium  resembles  iron. 
While  fairly  stable  in  dry  air,  it  oxidizes  quickly  in  moist  air. 
It  takes  fire  more  easily  than  magnesium,  and  melts  at  a 
lower  temperature  than  silver  and  at  a  higher  temperature 
than  antimony.  It  is  soluble  in  dilute  acids,  but  is  not 
attacked  by  concentrated  sulphuric  or  nitric  acid.  It  com- 
bines with  chlorine,  bromine,  and  iodine,  forming  salts.  Its 
specific  gravity  is  6.6. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical forms  of  the  two  classes  of  cerium  compounds: 

Oxides Ce2O3  CeO2 

Hydroxides Ce2O3-6H2O  2CeO2-3H2O 

Carbonates Ce2(CO3)3+  5H2O  Ce(CO3)2+  o.5H2O 

Chloride CeCl3 

Bromide CeBr3 

Iodide CeI3 

Perchlorate Ce(ClO4)  3+  8H2O 

*  Included  under  Ce2O3. 


CERIUM.  33 

Bromate  ........  Ce(BrO3)3-f9H2O 

lodate  ..........  Ce(IO3)3+  2H2O 

Fluorides  .......  CeF3  CeF4+  HaO 

Cyanide  .........  Ce(CN)3 

Ferrocyanides.  .  .  Ce4(FeCflN8)3+  3oH2O 

CeKFeC6Nfl+3H20 
Ferricyanide  .....  CeFeC8N6+  8H2O 

Sulphocyanide  .  .  Ce(CSN)3+  7H2O 
Sulphide  ........  Ce2S3 

Sulphite  ........  Ce2(S03)3+  3H2O 

Sulphates  .......  Ce2(SO4)3+  3,  5,  6,  8,  9,  and      Ce(SO4)2  +  4H2O 

i2H20 
Double  sulphates.  Ce2(SO4)3  •  3K2SO4+  2H2O         CeCSOJz  •  2K2SO4+  2H2O 

Ce2(S04)3  •  3Na2S04+  2H2O 

Ce2(S04)3-(NH4)2S04+8H20 
Nitrates  ........  Ce(NO3)3-f  6H2O  Ce(NO3)4 

Double  nitrates.  .Ce2(NO3)6-3Zn(NO3)2-|-  2Ce(NO3)4-4KNO3+3H2O 


Ce2(N03V  3Co(N03)2+  2Ce(NO3)4.4(NH4)NO3+ 

24H2O,  etc.  3H2O 

Phosphates  ......  CePO4  (CeO2)4  •  (P2O5)e+  26H2O 

Oxalate  .........  Ce2(C2O4)3 

Carbide  ......... 


B.  Characteristics.  Cerium  exists  in  compounds  in  two 
conditions  of  oxidation.  The  higher  or  eerie  salts  are 
easily  reduced  to  the  lower  or  cerous  condition  by  the 
ordinary  reducing  agents  (e.g.  H2S,  SO2,  H2C2O4,  etc.), 
and  the  cerous  salts  may  be  oxidized*  to  the  eerie  condition 
by  oxidizing  agents  (e.g.  PbO2  +  HNO3,  H2O2,  KMn04,  etc.). 
In  general  the  cerous  salts  are  colorless,  and  the  eerie  yellow. 
The  lower  oxide  of  cerium,  (Ce2O3),  on  ignition  goes  over  to 
the  higher  condition,  (CeO2).  The  cerous  salts  are  the  more 
stable,  and  consequently  they  form  the  greater  number. 
They  resemble  the  yttrium  salts  in  many  of  their  reactions, 
and  are  distinguishable  from  them  chiefly  by  the  formation 
of  the  double  sulphates  with  sodium  sulphate  and  potas- 
sium sulphate  respectively,  by  the  comparative  insolubility 
of  the  carbonate  in  ammonium  carbonate,  and  by  the  possi- 
bility of  oxidation  to  a  higher  condition.  Solutions  of  pure 
cerium  salts  give  no  absorption  spectra. 


34  THE  RARER  ELEMENTS. 

Estimation.  A.  Gravimetric.  Cerium  is  usually  deter- 
mined gravimetrically  as  the  dioxide,  (CeO2),  obtained  by 
the  ignition  of  the  hydroxide  or  the  oxalate. 

B.  Volumetric,  (i)  When  eerie  oxide,  (CeO2),  is  treated 
with  hydrochloric  acid  in  the  presence  of  potassium 
iodide,  iodine  is  set  free,  according  to  the  following 
equation : 

2CeO2  +  8HC1  +  2KI  =  2CeCl3  +  4H2O  +  2KC1  + 12. 

The  iodine  may  be  estimated  in  acid  solution  by  stand- 
ard thiosulphate,  or  in  alkaline  solution  by  standard 
arsenious  acid  (Bunsen,  Ann.  Chem.  Pharm.  cv,  49 ;  Brown- 
ing, Amer.  Jour.  Sci.  [4]  vui,  451). 

(2)  When  cerium  oxalate  is  dissolved  in  sulphuric  acid 
the  oxalic  acid  may  be  readily  determined  by  potassium 
permanganate,   and  the   amount  of   cerium  present  may 
be  thus  estimated  (Stolba,  Zeitsch.  anal.  Chem.  xix,  194; 
Browning,  Amer.  Jour.  Sci.  [4]  vm,  457). 

(3)  When   yellow  eerie   compounds   are   treated  with 
hydrogen  dioxide  in  acid  solution,   they  are  reduced  to 
cerous  compounds,  with  bleaching  of  color  (Knorre,  Zeitsch. 
angew.  Chem.   (1897),  685): 

2Ce  (S04)2  +  H202  =  Ce2(S04)3  +  H2SO4  +  O2. 

Separation.  Cerium  falls  into  the  analytical  group 
with  aluminum,  iron,  etc.  Together  with  the  other  rare 
earths  it  may  be  separated  from  these  by  oxalic  acid  or 
oxalate  of  ammonium.  For  separation  from  the  yttrium 
earths,  vid.  page  24. 

Cerium  may  be  separated  from  lanthanum  and  didy- 
mium  *  by  the  following  methods :  ( i )  by  treating  the  hy- 
droxides suspended  in  a  solution  of  caustic  potash  with 

*  For  an  instructive  review  of  the  methods  for  the  separation  of  cerium, 
lanthanum,  and  didymium,  see  P.  Mengel,  Zeitsch.  anorg.  Chem.  xix 
(1899),  67. 


CERIUM.  35 

chlorine  gas,  as  in  Experiment  33  (Mosander,  J.  pr.  Chem. 
xxx,  267) ;  (2)  by  treating  a  neutral  solution  of  the  cerium 
earths  with  an  excess  of  a  hypochlorite  and  boiling,  thus 
precipitating  eerie  oxide  (Popp,  Ann.  Chem.  Pharm.  cxxxi, 
359);  (3)  by  treating  a  solution  of  the  cerium  earths  with 
sodium  peroxide,  in  place  of  the  hypochlorite  in  (2)  (O.  N. 
Witt,  Chem.  Ind.  (1896),  u,  19);  (4)  by  treating  the  oxa- 
lates  of  the  cerium  earths  with  warm  dilute  nitric  acid; 
thus  separating  the  cerium  as  basic  nitrate  (Auer  von 
Welsbach,  Monatshefte  f.  Chem.  v,  508) ;  (5)  by  treating 
a  solution  of  the  salts  with  hydrogen  dioxide  in  the  presence 
of  magnesium  acetate  (Meyer  and  Koss,  Ber.  Dtsch.  chem. 
Ges.  xxxv,  672). 

From  thorium  cerium  may  be  separated  (i)  by  repeated 
precipitations  on  boiling  with  sodium  thiosulphate  (Fre- 
senius  and  Hintz,  Zeitsch.  anal.  Chem.  xxxv,  543) ;  (2)  by 
boiling  with  potassium  nitride  (Dennis  and  Kortright, 
Amer.  Chem.  Jour,  xvi,  79) : 

Th(NO3)4  +  4KN3  +  4H2O  =  Th(OH)4  +  4KNO3  +  4HN3 ; 

(3)  by  boiling  a  nearly  neutral  solution  of  the  chlorides 
with  copper  and  cuprous  oxide  (Lecoq  de  Boisbaudran, 
Compt.  rend,  xcix,  525) ;  (4)  by  the  action  of  fumaric  acid 
in  40%  alcohol  upon  solutions  of  the  salts  in  40%  alcohol 
(Metzger,  Jour.  Amer.  Chem.  Soc.  xxiv,  901).  In  all  of 
these  methods  the  thorium  is  precipitated. 

Cerium  is  separated  from  zirconium  by  fusion  of  the 
oxides  with  acid  potassium  fluoride,  and  extraction  with 
water  and  a  little  hydrofluoric  acid;  the  potassium  fluo- 
zirconate  is  dissolved,  and  the  thorium  and  cerium  remain  * 
(Delafontaine,  Chem.  News  LXXV,  230). 

Experimental  Work.     Vid.  Lanthanum  and  Didymium. 

*  For  the  action  of  organic  bases  as  precipitants  of  the  rare  earths,  vid. 
Jefferson,  Jour.  Amer.  Chem.  Soc.  xxiv,  540;  Baskerville,  Science,  New 
Series,  xvi,  215;  Kolb,  J.  pr.  Chem.  [2]  LXVI,  59;  Allen,  Jour.  Amer.  Chem. 
Soc.  xxv,  421. 


THE  RARER  ELEMENTS. 


LANTHANUM,  La,   138.77;  DIDYMIUM,  Di,   142.3. 

(PRASEODYMIUM,  Pr,   140.5;  NEODYMIUM,  Nd,  143.6.)" 

Discovery.  In  1839  Mosander  found  that  when  the 
nitrate  of  cerium  had  been  ignited,  he  was  able  to  extract 
from  it  by  very  dilute  acid  an  earth  which  differed  in  prop- 
erties from  that  of  cerium,  while  from  the  portion  remain- 
ing undissolved  he  obtained  the  reactions  of  the  cerium 
earth.  He  supposed  the  unknown  substance  of  the  newly 
discovered  earth  to  be  an  element,  and  named  it  Lan- 
thanum, from  \avQavziv,  to  hide  (Pogg.  Annal.  XLVI,  648; 
Liebig,  Annal.  xxxn,  235). 

In  1841,  while  engaged  in  further  work  upon  the  extrac- 
tion of  mixtures  of  cerium  and  lanthanum  oxides  by  dilute 
nitric  acid,  he  succeeded  in  separating  from  the  lanthanum 
oxide  another  earth,  rosy  in  color,  going  over  to  dark  brown 
on  being  heated.  Reserving  for  the  residual  oxide  the 
original  name  Lanthanum  earth,  he  called  the  base  of  the 
new  oxide  Didymium,  from  didvjuos,  twin,  —  a  name  sug- 
gested by  its  close  relationship  to  lanthanum  and  its 
almost  invariable  occurrence  with  it  (Pogg.  Annal.  LVI,  503). 

In  1885  Auer  von  Welsbach  announced  that  by  long- 
continued  fractional  crystallization  of  the  double  nitrates 
of  ammonium  with  lanthanum  and  didymium  in  the  pres- 
ence of  strong  nitric  acid,  he  had  separated  didymium 
into  two  elements  (Sitzungsber.  d.  k.  Acad.  d.  Wiss.  (1885) 
xcn,  Heft  I,  n,  317;  Ber.  Dtsch.  chem.  Ges.  xvin,  605). 
The  lanthanum  crystallized  out  first,  and  afterward  the 
decomposition  of  the  didymium  took  place.  To  these 
new  elements  he  gave  the  names  Praseodymium  (Ttpdcriros, 
leek-green)  and  Neodymium  (veos,  new). 

In  1888  Kriiss  and  Nilson  stated,  as  the  result  of  their 
work  on  the  absorption  spectrum  of  didymium,  that  they 


LANTHANUM ;  DIDYM1UM.  37 

had  discovered  indications  of  the  presence  of  no  less  than 
eight  elements  (Ber.  Dtsch.  chem.  Ges.  xx,  2134,  3067). 
These  results,  however,  have  not  as  yet  been  fully  con- 
firmed. At  the  present  time  the  existence  of  praseodym- 
ium and  heodymium  is  generally  accepted. 

(Though  the  term  "didymium"  does  not  designate 
an  element,  it  is  still  in  general  use,  and  for  the  sake  of 
convenience  it  is  employed  in  the  following  pages.  While 
there  is  a  considerable  body  of  information  concerning 
didymium,  its  constituent  elements  have  not  yet  been 
so  fully  studied, — perhaps  because  of  the  long  and  tedious 
operation  involved  in  their  separation.  For  that  reason, 
at  all  events,  no  experimental  work  on  them  is  given  in 
this  book.) 

Occurrence.  Lanthanum  and  didymium  are  found  al- 
most invariably  associated  with  cerium  (vid.  Occurrence 
of  Cerium). 

Extraction.  In  the  process  of  extracting  cerium  from 
cerite  (vid.  Experiment  33),  the  oxalates  of  cerium,  lan- 
thanum, and  didymium  are  precipitated  together.  Lan- 
thanum and  didymium  must  next  be  separated  from 
cerium,  and  then  from  each  other.  Afterward  didymium 
may  be  decomposed  into  its  two  constituents.  Several 
methods  of  accomplishing  these  three  steps  are  indicated 
under  Separation  of  Cerium,  and  of  Lanthanum  and  Didy- 
mium. 

The  Elements.  I.  LANTHANUM.  A.  Preparation.  The 
element  lanthanum  may  be  obtained  (i)  by  reducing 
the  chloride  with  potassium;  (2)  by  subjecting  the  double 
chloride  of  lanthanum  and  sodium  to  electrolysis. 

B.  Properties.  Lanthanum  is  a  metallic  element  of  a 
lead-gray  color.  It  decomposes  cold  water  slowly  and  hot 
water  more  rapidly,  with  the  evolution  of  hydrogen.  It 
oxidizes  easily  in  the  air.  Its  specific  gravity  is  from  6.04 
to  6.19. 


38  THE  R4RER  ELEMENTS. 

II.  DIDYMIUM.     Elementary   praseo-   and   neodymium 
have  not  been  isolated. 

A.  Preparation.     Didymium  may  be  prepared  from  the 
salts  by  the  methods  indicated  for  lanthanum  (vid.  Prep- 
aration of  Lanthanum). 

B.  Properties.      Metallic  didymium  is  yellowish  white. 
It  decomposes  cold  water  slowly  and  oxidizes  in  the  air. 
Its  specific  gravity  is  6.54. 

Compounds.     A.  Typical  forms.     The  following  are  typ- 
ical compounds  of  lanthanum  and  didymium: 

Oxides La2O8  Di2O3 

Di205 

Hydroxides La(OH)3  Di(OH)3 

Chlorides LaCl3+  7H2O  DiCl3+  6H2O 

Oxychlorides.  .  .  .IXOClj)  Di(OCl)3 

Chlorate La(ClO3)3 

Perchlorates La(ClO4)3+  9H2O  Di(ClO4)3+  9H2O 

Bromides LaBr3-f-  7H2O  DiBr3+  6H2O 

Bromates La(BrO3)3+9H2O  Di(BrO3)3+9H2O 

lodates La2(IO3)6+  3H2O  Di(IO3)3+  6H2O 

Periodates La(IO4)3+ 2H2O  Di(IO4)3+4H2O 

DiO(I04)+4H20 

Sulphites La2(SO3)3+  4H2O  Di2(SO3)3-f-  6H2O 

Sulphates La2(SO4)3+  9H2O  Di2(SO4)3-f  8H2O 

Double  sulphates.  La2(SO4)3  •  3K2SO4  Di2(SO4)3  •  3K2SO. 

La2(SO4)3  •  Na2SO4-f  2H2O  Di2(SO4)3 .  Na2SO4+  2H2O 

La2(S04)3  •  (NH4)2S04+  8H2O  Di2(SO4)3  i  (NH4)2SO4+  8H2O 

Dithionates La2(S2O6)3  +  i6H2O  Di2(S2O6)3  +  24H2O 

Selenites La2(SeO3)3+  9H2O  Di2(SeO3)3+  6H2O 

Seleniates La2(SeO4)3+  6H2O  Di2(SeO4)3+  8H2O 

Double  seleniates. La2(SeO4) 3  •  K2SeO4+  9H2O  Di2(SeO4)3  -  K2SeO4 

La2(SeO4)3  •  Na2SeO4+  4H2O  Di2(SeO4)3  •  Na2SeO4 

La2(Se04)3 .  (NH4)2SeO4+  Di2(SeO4)3  •  (NH4)2SeO4 
9H20 

Nitrates La(NO3)3+6H2O  Di(NO3)3+6H2O 

Phosphates LaPO4;  also  meta  and  pyro  DiPO4+H2O;  also  meta  and 

forms  PYr°  forms 

Arseniates La2H3(  AsO4)3  Di2H3(AsO4)3 

Arsenites La2H3(AsO3)3  Di2H3(AsO3)3 

Carbonates La2(CO3)3+  3H2O  Bi2(CO3)3+  6H2O ;  also  double 

salts  with  K,  Na,  and  NH« 
carbonates 


LANTHANUM;  D1DYMIUM.  39 


Oxalates  ........  La2(CaO4)s  Di2(C2O4)a 

Chromates  ......  La2(CrO4)3  Di2(CrO4)3 

Molybdates  ......  LaH3(MoO4)s  DiH^MoOJa 

Tungstates  ......  La2(WO4)3  Di(WO4)3 

Sulphides  .......  La2S3  Di2S3 

The  following  compounds  of  praseo-  and  neodymium 
have  been  described: 

Oxides  ..........  Pr2O3  •  Nd2O3 

Pr407 

Pr204  Nd204? 

Pr2O5?  Nd2O6? 

Carbonate  .......  Pr2(CO3)3-f-  8H3O 

Chlorides  ........  PrCl3+  7H2O  NdCl3+  6H2O 

Bromide  ........  PrBr3-|-  6H2O 

Sulphates  .......  Pr2(SO4)3+  8H2O  Nd2(SO4)3+  8H2O 

Pr202S04  Nd202S04 

PrH3(S04)3  NdH3(S04), 

Double  sulphates  .  Pr2(SO4)3  -  3K2SO4+  H2O 

Pr2(S04)3-(NH4)2S04+8H20 
Sulphides  .......  Pr2S3  Nd2S8 

Selenite  .........  Pr2(SeO3)3-H2SeO3+3H2O 

Seleniate  ........  Pr2(SeO4)3+  8H2O 

Double  seleniate  .  Pr2(SeO4)3  •  K2SeO4+  4H2O 

Nitrates  ........  Pr(NO3)3+  6H2O  Nd(NO3)3 

Double  nitrates.  .  Pr(NO3)3  •  2(NH4)NO3+  4H2O 

Pr(N03)3-2NaN03+H20 
Double  cyanide.  .  2Pr(CN)3-  Pt(CN)2+  i8H3O 
Oxalate  .........  Pr2(C2O4)3+  ioH2O 

B.  Characteristics.  The  compounds  of  lanthanum,  di- 
dymium,  and  cerium  in  the  cerous  condition  are  very 
similar  in  their  behavior  toward  chemical  reagents.  The 
compounds  of  lanthanum  and  didymium  may  be  distin- 
guished from  those  of  cerium  by  the  absence  of  yellow  color 
on  the  addition  of  oxidizing  agents,  —  a  color  character- 
istic of  the  higher  oxide  of  cerium.  Lanthanum  may  be 
distinguished  from  didymium  by  the  colorlessness  of  its 
salts  and  by  the  absence  of  an  absorption  spectrum.  Di- 
dymium salts  in  general  are  of  a  rosy  color  and  give  a 
distinctive  absorption  spectrum. 


40  THE  RARER  ELEMENTS. 

The  compounds  of  praseo-  and  neodymium  have  not 
been  sufficiently  studied  to  allow  any  detailed  description 
of  their  characteristics  to  be  given.  Neodymium  salts 
are  rose-colored  and  are  very  similar  in  appearance  and 
in  behavior  to  the  salts  of  the  original  didymium.  The 
oxide  Nd2O3  is  bluish.  Praseodymium  salts  are  green. 
While  their  chemical  form  resembles  closely  the  form  of 
the  neodymium  salts,  higher  oxides  are  definitely  known 
in  the  case  of  praseodymium.  The  ordinary  oxide  Pr2O3 
is  greenish  white ;  the  higher  oxide  Pr407  is  nearly  black. 
Each  of  the  two  elements  has  distinctive  spectra,  spark 
and  absorption.  Mixed,  the  elements  give  the  didymium 
spectrum. 

Estimation.  Like  cerium,  lanthanum  and  didymium 
are  generally  estimated  as  oxides,  obtained  by  ignition 
of  the  hydroxides  or  oxalates. 

Separation.  A.  Lanthanum  from  didymium.  Lantha- 
num may  be  separated  from  didymium  (i)  by  dissolv- 
ing the  sulphates  in  water  at  9°  C.  and  gradually  raising 
the  temperature, — the  lanthanum  sulphate  separating 
first  (Hermann,  J.  pr.  Chem.  LXXXII,  385) ;  (2)  by  heating 
the  nitrates  at  4oo°-5oo°  C.  and  extracting  with  water, — 
the  didymium  tending  to  form  an  insoluble  basic  nitrate 
(Damour  and  Deville,  Bull.  Soc.  Chim.  d.  Paris  n,  339) ; 
(3)  by  dissolving  half  of  a  given  amount  of  the  oxides  in 
warm  dilute  nitric  acid,  then  adding  the  other  half,  with 
constant  stirring,  cooling  the  mass,  and  extracting  with 
water  (vid.  Experiment  33).  The  didymium  will  be  found 
in  the  residue  (Auer  von  Welsbach,  Monatshefte  f.  Chem. 

v,  508). 

B.  Praseodymium  from  neodymium.  Didymium  may 
be  separated  into  its  two  constituents  (i)  by  making  several 
hundred  fractional  crystallizations,  first  of  the  double 
nitrate  of  ammonium  and  didymium  and  later  of  the 
double  nitrate  of  sodium  and  didymium,  in  the  presence  of 


EXPERIMENTAL   WORK  ON  CERIUM,    LANTHANUM,  ETC.       41 

nitric  acid, — the  neodymium  salt  being  the  more  soluble 
(Auer  von  Welsbach,  Sitzungsber.  d.  k.  Acad.  d.  Wiss. 
(1885)  xcn,  Heft  I,  n,  317;  (2)  by  allowing  nitric  acid 
to  act  upon  the  oxalates, — the  praseodymium  salt  being 
the  more  soluble  (Scheele,  Ber.  Dtsch.  chem.  Ges.  xxxn, 
417) ;  (3)  by  treating  the  sulphates  with  water, — the  praseo- 
dymium sulphate  being  the  more  soluble  (Muthmann  and 
Rolig,  Ber.  Dtsch.  chem.  Ges.  xxxi,  1718);  (4)  by  making 
fractional  precipitations  of  a  solution  of  didymium  nitrate 
by  means  of  sodium  acetate  and  hydrogen  peroxide, — 
the  praseodymium  separating  first  (Meyer  and  Koss,  Ber. 
Dtsch.  chem.  Ges.  xxxv,  676) ;  (5)  by  saturating  a  cold 
concentrated  solution  of  citric  acid  with  the  hydroxides 
free  from  ammonia  and  excess  of  water,  then  filtering 
and  heating, — the  green  citrate  of  praseodymium  being 
precipitated,  insoluble  in  hot  water  (Baskerville,  Science, 
New  Series,  xvi,  214). 

EXPERIMENTAL    WORK    ON    CERIUM,    LANTHA- 
NUM,   AND    DIDYMIUM. 

Experiment  33.  Extraction  of  cerium,  lanthanum,  and 
didymium  salts  from  cerite  (Ca,Fe)(CeO)(Ce2«3OH)(SiO3)3. 
Treat  25  grm.  of  finely  powdered  cerite  with  common 
sulphuric  acid  and  stir  until  the  mass  has  the  con- 
sistency of  thick  paste.  Heat  until  the  excess  of  sul- 
phuric acid  is  removed  and  then  keep  the  mass  for 
some  time  at  low  redness.  Cool,  pulverize,  and  digest 
with  cold  water  until  no  further  precipitate  appears  upon 
the  addition  of  ammonium  oxalate  to  a  few  drops  of  the 
extract.  Pass  hydrogen  sulphide  into  the  solution  to 
remove  traces  of  bismuth  and  copper.  Filter,  and  to  the 
filtrate  add  oxalic  acid  to  complete  precipitation  of  the 
oxalates  of  cerium,  lanthanum,  and  didymium.  Ignite  the 
oxalates,  and  dissolve  in  hydrochloric  acid  the  oxides 
obtained.  To  this  solution  add  potassium  hydroxide 


42  THE  RARER  ELEMENTS. 

until  the  precipitation  of  the  hydroxides  is  complete. 
Make  up  the  volume  of  the  liquid  in  which  the  hydroxides 
are  suspended  to  about  200  cm.3  Add  about  5  grm.  of 
potassium  hydroxide  to  insure  an  excess,  and  pass  a  slow 
current  of  chlorine  gas  through,  stirring  from  time  to  time, 
until  the  liquid  is  no  longer  alkaline  in  reaction  and  the 
precipitate  has  assumed  a  deep-yellow  color.  By  this 
process  the  cerium  hydroxide  is  oxidized  to  the  dioxide, 
which  remains  undissolved,  and  the  lanthanum  and  didy- 
mium  hydroxides  are  dissolved.  When  the  separation  is 
complete,  a  portion  of  the  washed  precipitate  dissolved  in 
hydrochloric  acid  should  give  no  evidence  of  the  presence 
of  didymium, — for  example,  no  absorption  spectrum  (vid. 
Experiment  43).  The  absence  of  didymium  at  this  point 
is  considered  sufficient  evidence  of  the  absence  of  lanthanum. 
To  the  solution  containing  the  lanthanum  and  didymium, 
the  cerium  dioxide  having  been  removed  by  filtration,  add 
oxalic  acid  until  the  precipitation  is  complete.  Filter 
off  the  oxalates,  wash,  dry,  and  ignite.  Dissolve  one  half 
of  the  oxides  obtained  by  this  process  in  the  least  possible 
amount  of  warm,  dilute  nitric  acid,  and  add  the  remainder 
of  the  oxides  to  the  solution.  Stir  thoroughly,  and  when 
the  mass  is  cool  extract  with  water.  The  didymium  tends 
to  be  in  the  residue  and  the  lanthanum  in  solution. 

Experiment  34.  Reduction  and  oxidation  of  cerium 
compounds,  (a)  To  a  small  portion  of  the  carefully  washed 
cerium  dioxide  obtained  in  the  previous  experiment  add 
a  little  hydrochloric  acid  diluted  with  an  equal  volume 
of  water  and  boil.  Note  the  evolution  of  chlorine  and 
the  ultimate  colorless  solution  of  cerium  chloride,  (CeCl3). 

(b)  To  a  portion  of  the  solution  obtained  in  (a)   add 
a  few  drops  of  ammonium  hydroxide  in  excess  and  some 
hydrogen    dioxide.       Note    the    orange-yellow   precipitate 
(CeO3?).     Other  oxidizing  agents,   such  as  sodium  hypo 
chlorite,   sodium  peroxide,   lead   dioxide,    potassium  per- 


EXPERIMENTAL    WORK  ON  CERIUM,  LANTHANUM,  ETC.       43 

manganate,  etc.,  may  be  used.  Boil  the  solution  holding 
the  precipitate  in  suspension  and  note  that  the  deep-yellow 
color  changes  to  a  lighter  yellow.  The  precipitate  becomes 
essentially  the  dioxide,  (CeO2). 

(c)  To  another  portion  of  the  washed  cerium  dioxide 
from  Experiment  33  (2CeO2-3H2O)  add  hydrochloric  acid 
as  before,  and  also  a  crystal  of  potassium  iodide  in  the 
cold.  Note  the  liberation  of  iodine  according  to  the 
reaction  2CeO2  +  8HC1  +  2KI  =  2CeCl3  +  2KC1  + 12  +  4H2O. 

Experiment  35.  Precipitation  of  cerous  hydroxide, 
(Ce(OH)3).  (a)  To  a  solution  of  cerium  chloride  add 
sodium,  potassium,  or  ammonium  hydroxide  in  solution. 
Note  the  insolubility  of  the  hydroxide  in  excess  of  these 
reagents. 

(b)  Repeat  the  experiment  with  tartaric  acid  present 
in  the  solution. 

Experiment  36.  Precipitation  of  cerous  carbonate, 
(Ce2(CO3)3).  (a)  To  a  solution  of  cerium  chloride  add  a 
solution  of  sodium  or  potassium  carbonate.  Note  the 
comparative  insolubility  in  excess. 

(b)  Repeat  the  experiment,  using  ammonium  carbonate 
as  the  precipitant. 

(c)  Try  the  action  of  the  common  acids  upon  the  car- 
bonate of  cerium. 

Experiment  37.  Precipitation  of  cerium  oxalate, 
(Ce2(C2O4)3).  (a)  To  a  solution  of  a  cerium  salt  add  oxalic 
acid  or  an  oxalate.  Note  the  crystalline  character  of  the  pre- 
cipitate, especially  after  the  liquid  has  been  stirred  and  boiled. 

(b)  Try  the  action  of  hydrochloric  acid  upon  cerium 
oxalate. 

Experiment  38.  Precipitation  of  the  double  sulphate 
of  cerium  and  potassium  or  sodium,  (Ce2(S04)3-3K2SO4  or 
Ce2(SO4)3-Na2SO4).  To  a  few  drops  of  a  concentrated 
solution  of  a  cerous  salt  add  a  small  portion  of  a  saturated 
solution  of  sodium  or  potassium  sulphate. 


44  THE  RARER  ELEMENTS. 

Experiment  39.  Precipitation  of  cerium  phosphate, 
(CePO4).  (a)  To  a  solution  of  a  cerous  salt  add  sodium 
phosphate  in  solution. 

(6)  Try  the  action  of  hydrochloric  and  acetic  acids 
upon  separate  portions  of  the  precipitate. 

Experiment  40.  Precipitation  of  cerous  fluoride,  (CeF3). 
To  a  solution  of  cerium  chloride  add  potassium  fluoride  in 
solution. 

Experiment  41.  Precipitation  of  the  ferrocyanide  of 
cerium,  (Ce4(FeC6N6)3).  (a)  To  a  solution  of  cerium  chloride 
add  potassium  ferrocyanide. 

(6)  Note  that  potassium  ferricyanide  gives  no  pre- 
cipitate. 

Experiment  42.  Comparison  of  lanthanum  and  didym- 
ium  with  cerium.  (a)  Perform  Experiments  35  to  41 
inclusive  upon  dilute  solutions  of  lanthanum  and  didym- 
ium  salts. 

(6)  Note  that  pure  lanthanum  and  didymium  salts 
give  no  change  of  color  with  oxidizing  agents.  Compare 
with  cerium  salts  (vid.  Experiment  34). 

Experiment  43.  Didymium  absorption  spectrum.  Place 
a  solution  of  a  didymium  salt  between  the  slit  of  the 
spectroscope  and  a  luminous  flame.  Note  the  dark  bands. 
Observe  that  cerium  and  lanthanum  salts  in  solution  show 
no  absorption  bands  when  free  from  didymium. 

Experiment  44.  Negative  test  of  the  salts  of  cerium, 
lanthanum,  and  didymium.  Note  that  hydrogen  sulphide 
gives  no  precipitate  with  salts  of  this  group.  Ammonium 
sulphide  precipitates  the  hydroxides,  not  the  sulphides. 

THORIUM,  Th,  232.5. 

Discovery.  As  early  as  the  year  1818  Berzelius,  after 
working  on  a  mineral  from  Fahlun,  Sweden,  believed  that 
he  had  discovered  a  new  earth  (Annal.  der  Phys.  u.  Chem. 


THORIUM.  45 

(1818)  xxix,  247).  He  gave  it  the  name  Thoria,  from 
Thor,  son  of  the  Scandinavian  war  god  Odin.  Some  years 
later  however,  he  identified  the  supposed  new  earth  as 
chiefly  a  basic  phosphate  of  yttrium  (Pogg.  Annal.  iv, 
145).  In  1828  Esmark  discovered,  near  Brevig,  Norway, 
the  mineral  since  known  as  thorite.  From  it  Berzelius 
isolated  an  unknown  earth;  its  similarity  to  the  substance 
described  by  him  some  ten  years  earlier  prompted  the 
name  Thoria  (Pogg.  Annal.  xvi,  385). 

Occurrence.      Thorium  is  found  in  combination  in  cer- 
tain rare  minerals : 

Contains  ThO2 

Thorite  or  orangite,  ThSiO4 48-72% 

Yttrialite,  R2O3  -  2SiO2 12  % 

Zircon,  ZrSiO4. 0-2% 

ii  in 
Orthite  or  allanite,  HRR3Si3O13 0-3% 

Mackintoshite,  UO^ThO^SiO^H.O 45-46%* 

Thorogummite,  UO3  -  3ThO2  •  3SiO2  •  6H20 41-42  % 

Caryocerite,  complex  silicates :  13-14% 

Tritomite,  "  "       8-9% 

Zirkelite,  (Ca,Fe)O  -  2(Zr,Ti,Th)O2 7-8% 

Monazite,  (Ce^a.D^PO, 0-18% 

Xenotime,  YPO4 0-3% 

in                in 
JEschynite,  RJNb4Ou-Rt('Ii,Th)iOu 15-1?% 

Ill  III 

Euxenite,  R(NbO3)3  -  R2(TiO3)3  •  f  H2O o-  6 % 

Tscheffkinite,  complex  silico-titanates 0-21  % 

Pyrochlore,  RNbaO6-R(Ti,Th)O3 0-8% 

n  in 

Samarskite,  R^Nt^Ta)^ o-  3% 

o 

Annerodite,  formula  doubtful 2-  3% 

Polymignite,  5RTiOs  •  5RZrO3  •  R(Nb,Ta)aO6 3-4% 

*ThO,+  Ce208. 


46  THE  RARER  ELEMENTS. 

Extraction.  Two  common  methods  for  the  extraction 
of  thorium  salts  are  here  indicated: 

(1)  From    thorite.     The    mineral    is    decomposed    by 
heating  it  with  sulphuric  acid  (vid.  Experiment  33).  After 
the  extraction  of  the  sulphate  with  cold  water,  the  solution 
is  heated  to  100°  C.  and  an  impure  sulphate  of  thorium 
comes  down.     By  repeated  solution  of  the  precipitate  in 
cold  water  and  reprecipitation  by  means  of  heat  a  pure 
sulphate   is   finally   obtained    (Delafontaine,   Ann.    Chem. 
Pharm.   cxxxi,    100). 

(2)  From   monazite.     The   mineral   is   decomposed   by 
sulphuric  acid  and  the  oxalates  are  precipitated  by  oxalic 
acid  (vid.  Experiment  45). 

The  Element.  A.  Preparation.  Elementary  thorium 
may  be  obtained  (i)  by  heating  the  double  chloride  of 
thorium  and  potassium  with  metallic  sodium  (Nilson); 
(2)  by  reducing  the  double  fluoride  of  potassium  and 
thorium  with  potassium. 

B.  Properties.  Thorium  is  known  in  two  forms,  (i) 
that  of  a  grayish,  glistening  powder,  and  (2)  crystalline. 
It  is  stable  in  the  air,  and  does  not  decompose  water,  even 
at  1 00°  C.  When  heated  in  a  current  of  chlorine,  bromine, 
or  iodine  it  glows  and  forms  the  salt.  It  is  soluble  in 
dilute  hydrochloric  and  sulphuric  acids,  in  concentrated 
sulphuric  acid  with  the  liberation  of  sulphur  dioxide,  and 
in  aqua  regia.  It  is  acted  upon  very  slowly  by  nitric 
acid,  and  is  not  attacked  by  the  alkali  hydroxides.  The 
specific  gravity  of  thorium  in  the  amorphous  condition 
is  10.97;  in  crystalline  form  11.2. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  thorium: 

Oxides,  ThO2;  Th2O7. 
Hydroxide,  Th(OH)4. 
Chlorides,  ThCl4;  also  double  salts  with  KC1  and  NH4C1. 


THORIUM.  47 

Bromide,  ThBrr 

Iodide,  ThI4. 

Fluoride,  ThF4  +  4H2O. 

Chlorate,  Th(ClOs)4. 

Perchlorate,  Th(ClO4)4. 

Bromate,  Th(BrO3)4. 

lodate,  Th(IO3)4. 

Sulphite,  Th(SO3)2  +  H2O. 

Sulphates,  Th(SO4)2  +  9H2O;  also  double  salts  with  K2SO4; 

Na2SO4;  and  (NH4)2SO4. 
Selenite,  Th(SeO3)2  +  H2O. 
Seleniate,  Th(SeO4)2  +  9H2O. 
Nitrate,  Th(NO3)4  +  i2H2O. 
Phosphate,  Th3(PO4)4  +  4H2O. 
Pyrophosphate,   ThP2O7  +  2 H2O. 
Ferrocyanide,  ThFe(CN)6  +  4H2O. 
Silicate,   ThSi04. 

Carbonates,  Th(CO3)2 ;  Th(CO3)2  •  sNa2CO3  + 1 2H2O. 
Oxalate,  Th(C2O4)2  +  2H2O. 
Sulphide,  ThS2. 

B.  Characteristics.  The  compounds  of  thorium  resem- 
ble in  chemical  form  those  of  cerium  in  the  eerie  con- 
dition. Thorium  resembles  cerium  also  in  having  a  hy- 
droxide insoluble  in  the  alkali  hydroxides,  and  in  forming 
a  double  sulphate  with  potassium  sulphate,  insoluble  in 
excess  of  that  precipitant.  The  salts  of  thorium  are  colorless 
except  where  the  element  is  combined  with  an  acid  having  a 
color  of  its  own.  Possibly  the  most  distinctive  reactions  of 
thorium  compounds  are  the  ready  formation  of  a  soluble 
double  oxalate  when  ammonium  oxalate  is  added  in  excess 
to  a  thorium  salt  in  solution,  and  the  precipitation  of  the 
hydroxide  when  a  solution  of  a  thorium  salt  is  boiled  with 
potassium  hydronitride  (Dennis  and  Kortright,  Amer. 
Chem.  Jour,  xvi,  79). 

Estimation.      Thorium  is  ordinarily  estimated  as    the 


48  THE  RARER  ELEMENTS. 

oxide  (ThO2),  obtained  by  ignition  of  the  hydroxide,  the 
nitrate,  or  the  oxalate. 

Separation.  Thorium  is  a  member  of  the  aluminum 
group.  Together  with  the  rare  earths  cerium,  yttrium, 
zirconium,  etc.,  it  may  be  separated  from  other  members 
of  the  group  by  oxalic  acid.  Methods  for  its  separation 
from  yttrium  and  cerium  have  already  been  given  (vid. 
pages  24  and  35). 

From  zirconium  thorium  may  be  separated  (i)  by  the 
action  of  acids  upon  the  potassium  double  sulphates, — • 
the  zirconium  salt  being  the  more  soluble  5(2)  by  the  action 
of  an  excess  of  oxalic  acid  upon  the  oxalates, — the  zir- 
conium oxalate  dissolving  first;  (3)  by  fusion  with  acid 
potassium  fluoride;  (4)  by  the  action  of  dimethylamine 
upon  solutions  of  the  salts, — thorium  hydroxide  being  pre- 
cipitated (Kolb,  J.  pr.  Chem.  [2]  LXVI,  59). 

EXPERIMENTAL    WORK    ON    THORIUM. 

Experiment  45.  Extraction  of  thorium  oxide  from  mona- 
zite.  Treat  25  grm.  of  finely  ground  monazite  with  com- 
mon sulphuric  acid  according  to  the  method  already 
described  (vid.  Experiment  33).  Precipitate  the  oxalates 
with  oxalic  acid, — not  ammonium  oxalate, — boil,  and  col- 
lect on  a  filter.  Treat  the  precipitate  with  a  large  excess 
of  ammonium  oxalate  and  boil.  Cool,  filter,  and  to  the 
filtrate  add  hydrochloric  acid.  Collect  and  ignite  the 
oxalate  of  thorium  thus  precipitated. 

Note.     This  method  may  be  employed  for  the  extraction 
of  thorium  from  discarded  Welsbach-light  mantles. 

Experiment  46.  Precipitation  of  thorium  hydroxide, 
(Th(OH)4).  (a)  To  a  solution  of  a  thorium  salt  add  sodium, 
potassium,  or  ammonium  hydroxide.  Note  the  insolu- 
bility of  the  hydroxide  in  excess  of  the  precipitant. 

(b)  To  a  solution  of  a  thorium  salt  add  sodium  thio- 
sulphate  in  solution  and  boil. 


EXPERIMENTAL   WORK  ON   THORIUM.  49 

Experiment  47.  Precipitation  of  thorium  carbonate, 
(Th(CO8)2).  (a)  To  a  solution  of  a  thorium  salt  add 
potassium  or  sodium  carbonate.  Note  the  solubility  of 
the  precipitate  in  excess  and  the  reprecipitation  on  boiling. 

(b)  Repeat,  using  ammonium  carbonate. 

(c)  Note  the  solvent  action  of  the  common  acids  upon 
thorium  carbonate. 

Experiment  48.  Precipitation  of  the  oxalate  of  thorium, 
(Th(C2O4)2  +  2H2O).  (a)  To  a  solution  of  a  thorium  salt 
add  a  solution  of  oxalic  acid.  Note  the  insolubility  in 
excess  of  the  precipitant. 

(b)  Repeat,  using  ammonium  oxalate  as  the  precipitant. 
Note  the  solubility  in  excess,  especially  on  warming,  and 
the  reprecipitation  upon  the  addition  of  hydrochloric  acid. 

(c)  Try  the  solvent  action  of  ammonium  acetate  upon 
thorium  oxalate. 

Experiment  49.  Precipitation  of  the  double  sulphate 
of  potassium  and  thorium,  (Th(SO4)2-2K2SO4  +  2H2O  or 
Th(SO4)2  -  4K2SO4  +  2H2O) .  Saturate  a  solution  of  a  thorium 
salt  with  potassium  sulphate.  (The  corresponding  sodium 
salt  (Th(SO4)2-Na2SO4  +  6H2O)  is  somewhat  soluble  in 
excess  of  sodium  sulphate.) 

Experiment  50.  Precipitation  of  thorium  phosphate, 
(Th3(PO4)4  +  4H2O).  To  a  solution  of  a  thorium  salt  add 
sodium  phosphate  in  solution.  Orthophosphoric  acid  is 
said  to  precipitate  an  acid  phosphate  (ThH2(PO4)2). 

Experiment  51.  Precipitation  of  thorium  fluoride, 
(ThF4  +  4H2O).  To  a  solution  of  a  thorium  salt  add  a 
solution  of  potassium  fluoride.  Double  salts  with  thorium 
fluoride  may  also  form  (#KF-yThF4  typical). 

Experiment  52.  Precipitation  of  thorium  ferrocyanide , 
(ThFe(CN)8  +  4H2O).  To  a  solution  of  a  thorium  salt  add 
a  solution  of  potassium  ferrocyanide.  Note  the  absence 
of  precipitation  with  potassium  ferricyanide. 

Experiment    53.     Action    of    hydrogen    peroxide    upon 


50  THE  RARER  ELEMENTS. 

salts  of  thorium.     To  a  solution  of  a  thorium  salt  add  a 
little  hydrogen  peroxide,  and  warm. 

Experiment  54.  Negative  test  of  thorium  salts.  To  a 
solution  of  a  thorium  salt  add  hydrogen  sulphide.  Note 
that  ammonium  sulphide  precipitates  the  hydroxide,  not 
the  sulphide. 

ZIRCONIUM,   Zr,    90.7. 

Discovery.  While  engaged  in  the  analysis  of  the 
zircons,  in  1788,  Klaproth  found  one  variety  containing 
31.5%  of  silica,  0.5%  of  the  oxides  of  iron  and  nickel, 
and  68%  of  an  earth  which  differed  from  all  earths  pre- 
viously known  to  him.  He  observed  that  it  was  soluble 
in  the  acids,  but  insoluble  in  the  alkalies,  in  the  latter 
respect  differing  from  alumina  (Ann.  de  Chim.  i,  238). 
The  fact  that  zircon  was  the  source  of  the  new  earth  sug- 
gested the  name  Zirconium  for  the  element. 

Occurrence.  Zirconium  is  found  combined,  widely  dif- 
fused, but  always  in  small  quantities. 

Contains  ZrO2 

Zircon,  ZrSiO4 61-67% 

Rosenbuschite,  6CaSiO3-2Na2ZrO2F2-(TiSiO3-Ti03)  18-20% 

Lavenite,  R(Si,Zr)O3-Zr(SiO3)2-RTa2O6 28-32% 

Wohlerite,  i2R(Si,Zr)O3-RNb,O6 15-23% 

Hainite,  allied  to  lavenite,  etc .undetermined 

Hiortdahlite,  4Ca(Si,Zr)O3-Na2ZrO2F2 21-22% 

Eudialyte,  Na13(Ca,Fe)6Cl(Si,Zr)20O52 "-17% 

Catapleiite,  H4(Na2,Ca)ZrSi3On 29-40% 

Elpidite,  H6Na2ZrSi6O18 20-21  % 

Eucolite,  vid.  Eudialyte 12-16% 

Auerbachite,  vid.  Zircon 38-69% 

Cyrtolite,          "        "     41-42% 

Alvite,                        'V 48-51% 

Tritomite,  complex  silicates i-  2  % 

Erdmannite,     "            "       0-5% 


ZIRCONIUM.  51 

Contains  ZrO2 

Polymignite,  5RTiO8-5RZrO3-R(Nb,Ta)2Ofl 29-30% 

Arrhenite,  complex 3-  4% 

Sipylite,          V       2-3% 

Zirkelite,  (Ca,Fe)O •  2(Zr,Ti,Th)O2 52-53% 

Baddeleyite,  ZrO2 96 •  5% 

Extraction.  Zirconium  salts  may  be  extracted  from 
zircon  by  the  following  methods: 

(1)  The  finely  powdered  mineral  is  fused  with  acid 
potassium  fluoride  (vid.  Experiment  55)  (Marignac,  Ann. 
Chim.  Phys.  [3]  LX,  257). 

(2)  The   mineral  is  fused  with  potassium  bisulphate 
and  the  fused  mass  extracted  with  dilute  boiling  sulphuric 
acid.     The  basic  sulphate  (3ZrO-SO3)  is  left  as  a  residue 
(Franz,  Ber.  Dtsch.  chem.  Ges.  n,  58). 

(3)  The  finely  powdered  mineral  is  heated  with  a  mix- 
ture of  sodium  hydroxide  and  sodium  fluoride,  the  mass 
is    cooled,    pulverized,    and   extracted   with   water.     The 
residue,    which   consists   mainly   of   sodium   zirconate,    is 
digested    with    hydrochloric    acid   until    dissolved.     After 
the  solution  has  been  evaporated  to  a  small  volume  the 
zirconium  oxychloride  separates  in  crystalline  form  (Bailey, 
Proc.  Royal  Soc.  XLVI,   74). 

The  Element.  A.  Preparation.  Elementary  zirconium 
maybe  obtained  in  the  amorphous  condition  (i)  by  reducing 
potassium  fluozirconate  with  potassium  (Berzelius),  and  (2) 
by  reducing  the  oxide  with  magnesium  (Phipson).  It  may 
be  obtained  in  crystalline  form  by  heating  potassium 
fluozirconate  with  aluminum  (Troost),  and  in  graphitic 
form  by  heating  sodium  fluozirconate  with  iron  at  850°  C. 

B.  Properties,  (i)  Zirconium  in  the  amorphous  con- 
dition is  a  black  powder.  Heated  in  the  air  it  burns 
brightly  to  the  oxide.  It  oxidizes  also  when  fused  with 
alkali  nitrates,  carbonates,  and  chlorates,  and  is  only 
slightly  attacked  by  acids. 


52  THE  RARER  ELEMENTS. 

(2)  In  crystalline  form  zirconium  has  much  the  ap- 
pearance of  antimony.  Heated  in  the  air  it  oxidizes  very 
slowly.  It  is  not  acted  upon  by  fusion  with  alkali  nitrates, 
carbonates,  or  chlorates,  but  is  soluble  in  the  acids  upon 
the  application  of  heat.  Its  specific  gravity  is  4.15. 

Compounds.  A.  Typical  forms.  The  following  are 
typical  compounds  of  zirconium: 

Oxides,  ZrO2;  ZrO3. 

Hydroxide,    Zr(OH)4. 

Chlorides,  ZrCl4;  also  double  salts  with  KC1  and  NaCl. 

Oxyhalides,  ZrOCl2+3H2O ;  ZrOBr2+3H2O ;  ZrI(OH)3+3H2(X 

Bromide,  ZrBr4. 

Iodide,   ZrI4. 

Fluoride,  ZrF4. 

Sulphite,  Zr(S03)2. 

Sulphates,  Zr(SO4)2  +  4H2O;  3ZrO2-S03. 

Selenite,   Zr(Se03)2. 

Nitrate,   Zr(N03)4  +  sH2O. 

Phosphate,   Zr3(PO4)4. 

Pyrophosphate,   ZrP2O7. 

Carbonate,   3ZrO2-CO2  +  8H2O. 

Oxalates,  Zr(C2O4)2-2Zr(OH)4;  Zr(C2O4)2-K2C2O4.H2C2O4-f 

8H2O. 

Zirconates,  Na4ZrO4;  Li2ZrO3,  etc. 
Fluozirconate,  K2ZrF6. 

B.  Characteristics.  In  chemical  structure  the  com- 
pounds of  zirconium  bear  a  strong  resemblance  to  those 
of  thorium,  titanium,  germanium,  and  silicon.  The  oxide, 
in  its  behavior  as  a  base  toward  oxides  having  more  acidic 
qualities,  resembles  the  oxide  of  thorium  (ThO2).  With 
the'  weaker  acids,  carbonic  and  oxalic,  it  shows  weaker 
basic  properties  in  the  formation  of  basic  salts.  With 
strong  bases  it  manifests  acidic  properties,  like  the  oxide 
of  titanium,  and  forms  zirconates  (vid.  Typical  Forms, 


ZIRCONIUM.  53 

above).  The  hydroxide  of  zirconium  is  insoluble  in  excess 
of  the  alkali  hydroxides,  the  double  sulphate  with  potas- 
sium is  insoluble  in  a  solution  of  potassium  sulphate,  and 
the  oxalate  is  soluble  in  ammonium  oxalate.  Solutions 
of  pure  zirconium  salts  are  said  to  give  no  precipitate  with 
hydrofluoric  acid  or  potassium  hydronitride.  Turmeric 
paper,  when  dipped  into  a  solution  of  a  zirconium  salt  and 
dried,  is  colored  orange. 

Estimation.  Zirconium  is  usually  weighed  as  the  oxide 
(ZrO2)  obtained  by  ignition  of  the  hydroxide  or  oxalate. 

Separation.  Zirconium  is  a  member  of  the  aluminum 
group,  and  with  the  rare  earths  may  be  roughly  separated 
from  other  members  of  the  group  by  the  action  of  oxalic 
acid  (vid.  page  24).  For  the  separation  from  yttrium, 
cerium,  and  thorium  see  under  those  elements.  The  sepa- 
ration of  zirconium  from  iron  and  titanium  has  received  a 
good  deal  of  attention  from  chemists.  Some  of  the  methods 
that  have  been  suggested  follow. 

From  iron  zirconium  may  be  separated  (i)  by  the  action 
of  water  upon  an  ethereal  solution  of  the  chlorides, — the 
oxychloride  of  zirconium  being  precipitated  (Matthews, 
Jour.  Amer.  Chem.  Soc.  xx,  846) ;  (2)  by  the  action  of 
gaseous  hydrochloric  acid  and  chlorine  at  a  temperature  of 
about  200°  C.  upon  the  mixed  oxides, — the  ferric  chloride 
being  volatilized  (Havens  and  Way,  Amer.  Jour.  Sci,  [4] 
vin,  217);  (3)  by  treatment  with  phenylhydrazine, — the 
zirconium  being  precipitated  (Allen,  Jour.  Amer.  Chem. 
Soc.  xxv,  426) ;  (4)  by  the  action  of  sulphurous  acid 
on  neutral  solutions, — the  zirconium  being  precipitated 
(Baskerville,  Jour.  Amer.  Chem.  Soc.  xvi,  475). 

From  titanium  zirconium  may  be  separated  (i)  by 
boiling  a  solution  containing  the  two  elements  with  dilute 
sulphuric  and  acetic  acids, — titanic  acid  being  precipitated 
free  from  zirconium  (Streit  and  Franz,  J.  pr.  Chem.  cvm, 
75 ;  Zeitsch.  anal.  Chem.  ix,  388) ;  (2)  by  treating  solu- 


54  THE  RARER  ELEMENTS. 

tions  acid  with  sulphuric  or  hydrochloric  acid  with  zinc 
until  the  titanium  is  reduced  to  the  condition  of  the  sesqui- 
oxide,  and  then  adding  potassium  sulphate, — the  zirconium- 
potassium  sulphate  being  precipitated  (Pisani,  Compt. 
rend.  LVII,  298;  Chem.  News  x,  91,  218);  (3)  by  adding 
ammonium  hydroxide  to  a  boiling  hydrofluoric  acid  solu- 
tion of  the  salts, — the  titanic  acid  being  precipitated 
(Demarcay,  Compt.  rend,  c,  740;  J.  B.  (1885),  1929). 

EXPERIMENTAL    WORK    ON    ZIRCONIUM. 

Experiment  55.  Extraction  of  zirconium  salts  from 
zircon.  Fuse  5  grm.  of  finely  powdered  zircon  in  a  platinum 
or  nickel  crucible  with  about  15  grm.  of  acid  potassium 
fluoride.  Pulverize  the  fused  mass  and  extract  with  hot 
water  containing  a  few  drops  of  hydrofluoric  acid.*  Filter 
immediately  through  a  rubber  funnel  into  a  rubber  beaker. 
As  the  filtrate  cools,  potassium  fluozirconate  crystallizes 
out.  It  may  be  purified  by  recrystallization. 

Experiment  56.  Precipitation  of  zirconium  hydroxide, 
(Zr(OH)4).  (a)  To  a  solution  of  a  zirconium  salt  add  potas- 
sium, sodium,  or  ammonium  hydroxide.  Note  the  insolu- 
bility in  excess.  (6)  To  a  solution  containing  zirconium  add 
sodium  thiosulphate  in  solution  and  boil. 

Experiment  57.  Precipitation  of  zirconium  carbonate, 
(3ZrO2-CO2  +  8H2O).  (a)  To  a  solution  of  a  zirconium 
salt  add  sodium  or  potassium  carbonate.  Note  the  partial 
solubility  in  excess. 

(6)  Use  ammonium  carbonate  as  the  precipitant.  Note 
the  solvent  action  of  an  excess  and  the  precipitation  of 
the  hydroxide  on  boiling. 

(c)  Try  the  action  of  the  common  acids  upon  separate 
portions  of  zirconium  carbonate. 

*  Glass  or  porcelain  dishes  must  not  be  used  when  hydrofluoric  acid  is 
present. 


GERMANIUM.  55 

&+**  *  * 

Experiment  58.  Precipitation  of  zirconium  oxalate, 
(Zr(C2O4)2-2Zr(OH)4).  (a)  To  a  solution  of  a  zirconium 
salt  add  a  solution  of  oxalic  acid.  Note  the  effect  of  an 
excess  in  the  cold  and  on  warming. 

(b)  Use  ammonium  oxalate  as  the  precipitant.  Note 
the  solvent  action  of  an  excess  and  the  reprecipitation  by 
ammonium  hydroxide. 

Experiment  59.  Precipitation  of  zirconium  phosphate, 
(xZrO2-yP2O5,  basic).  To  a  solution  of  a  zirconium  salt 
add  sodium  phosphate.  Orthophosphoric  acid  precipi- 
tates the  normal  phosphate  (Zr3(PO4)4). 

Experiment  60.  Precipitation  of  zirconium  ferrocyanide, 
(ZrFeC6N6?).  To  a  solution  of  a  zirconium  salt  add  potas- 
sium ferrocyanide. 

Experiment  61.  Action  of  zirconium  salts  upon  turmeric 
paper.  Dip  a  piece  of  turmeric  paper  into  a  solution  of  a 
zirconium  salt  acidified  with  hydrochloric  acid.  Dry  on  the 
side  of  a  test-tube  or  beaker,  as  in  testing  for  boric  acid. 
Note  the  yellowish-red  color. 

Experiment  62.  Negative  tests  of  zirconium  salts.  Note 
that  neither  hydrogen  sulphide  nor  potassium  fluoride  gives 
a  precipitate  with  zirconium  salts.  Ammonium  sulphide 
precipitates  the  hydroxide,  not  the  sulphide. 

GERMANIUM,  Ge,  72. 

Discovery.  In  1886  Clemens  Winkler  announced  the 
presence  of  a  new  element  in  the  silver  mineral  argyrodite, 
which  had  been  discovered  the  previous  year  by  Weisbach, 
in  the  Himmelsfurst  mine  near  Freiberg  (Ber.  Dtsch. 
chem.  Ges.  xix,  210).  According  to  Winkler 's  analysis 
of  argyrodite,  the  sum  of  its  component  parts  was  seven  per 
cent,  less  than  it  should  have  been;  and  although  he  re- 
peated the  analysis  several  times  with  great  care,  the  out- 
come was  always  the  same.  This  uniformity  of  result  forced 


56  THE  RARER  ELEMENTS. 

upon  him  the  conclusion  that  an  unknown  element  was 
probably  present  ;  and  after  much  careful  and  patient  work 
he  was  successful  in  isolating  it  and  investigating  its  prop- 
erties. On  heating  the  mineral  out  of  contact  with  the  air, 
he  obtained  a  dark-brown  fusible  sublimate,  which  proved 
to  be  chiefly  two  sulphides,  that  of  the  new  element,  named 
by  him  Germanium,  and  the  sulphide  of  mercury. 

Occurrence.     Germanium  is  found  in  combination  in  a 
few  rare  minerals. 

Contains 
Ge 

Argyrodite,  4Ag2S-GeS2  ........................  J.    6-7% 

Canfieldite,  4Ag2S  •  (Ge,Sn)S2  ......................  1.82% 


Euxenite,  R(NbOJ*  •  lnSO,),  '££^0  ...............  traces 

Extraction.      Germanium     salts    have     been    extracted 
from  argyrodite  by  the  following  methods: 

(1)  A  Hessian  crucible  is  heated  to  redness,  and  small 
quantities  of  a  mixture  consisting  of  three  parts  of  sodium 
carbonate,  six  parts  of  potassium  nitrate,  and  five  parts  of 
the  mineral  are  gradually  put  in.      After  being  heated  for 
some  time  the  molten  mass  is  poured  into  an  iron  dish  and 
allowed  to  cool.     The  salt  mass  may  then  be  removed  from 
the    silver,    pulverized,    and   extracted   with   water.     The 
extract  is   treated    with    sulphuric    acid    and    evaporated 
until  all  the  nitric  acid  is  driven  off.     The  residue  is  dis- 
solved in  water  and  allowed  to  stand  until  the  oxide  of 
germanium  separates  from  the  solution. 

(2)  The  mineral  is  heated  to  redness  in  a  current  of 
hydrogen,  and  the  sublimate,  consisting  of  a  mixture  of 
germanium    and    mercuric    sulphides,    is    collected.     This 
sublimate  is  treated  with  ammonium  sulphide,  which  dis- 
solves the  sulphide  of  germanium,  forming  a  sulpho  salt. 
After  filtration,  the  solution  is  acidified  with  hydrochloric 
acid,  which  precipitates  the  germanium  as  ftie  sulphide. 


GERMANIUM.  57 

The  Element.  A.  Preparation.  Elementary  germanium 
may  be  obtained  (i)  by  heating  the  oxide  with  carbon; 
(2)  by  heating  the  oxide  in  a  current  of  hydrogen. 

B.  Properties.  Germanium  is  a  grayish-white,  metallic 
element,  having  a  fine  luster,  and  crystallizing  in  regular 
octahedra.  It  volatilizes  slightly  when  heated  in  hydrogen 
or  nitrogen  at  about  1350°  C.;  its  melting-point  is  about 
900°  C.  In  the  air  it  does  not  oxidize  at  ordinary  tem- 
peratures, but  when  heated  goes  over  to  the  oxide  GeO2. 
It  is  not  attacked  by  dilute  hydrochloric  acid,  is  oxidized 
by  nitric  acid,  and  is  dissolved  by  aqua  regia.  It  is  dis- 
solved also  by  sulphuric  acid,  with  the  evolution  of  sul- 
phur dioxide.  It  combines  directly  with  chlorine,  bromine, 
and  iodine.  Its  specific  gravity  is  5.46. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  germanium: 

Oxides GeO  Ge02 

Hydroxides Ge(OH)2  Ge(OH)4? 

Chlorides GeCl2  GeCl4 

Oxychloride GeOCl2 

Bromide GeBr4 

Iodide GeI4 

Fluorides GeF2?  GeF4? ;  K2GeF6;  H2GeF6 

Sulphides GeS  GeS2 

Chloroform GeHCl3 

Ethyl Ge(C2H5)4 

B.  Characteristics.  The  germanium  compounds  are 
known  in  two  conditions  of  oxidation;  those  of  the  higher 
form  are  the  more  stable  and  comprise  the  larger  group. 
Germanium  resembles  carbon  and  silicon  in  the  formation 
of  a  chloroform,  and  tin  in  the  formation  of  two  sulphides 
which  dissolve  in  ammonium  sulphide,  giving  sulpho  salts. 
The  sulphide  GeS2  is  a  white  powder  slightly  soluble  in 
water.  The  lower  sulphide,  GeS,  when  precipitated,  is  of  a 


58  THE  R4RER  ELEMENTS. 

reddish -brown  color ;  when  obtained  by  the  reduction  of  the 
higher  sulphide  it  is  a  grayish -black  crys"  alline  substance  of 
metallic  luster.  This  sulphide,  also,  is  slightly  soluble  in 
water.  The  dioxide  is  a  white  powder  soluble  in  alkalies,  but 
almost  completely  insoluble  in  acids.  The  tetrachloride  is 
a  liquid  which  fumes  in  damp  air  and  is  decomposed  by 
water. 

Estimation.  Germanium  is  usually  precipitated  as  the 
sulphide,  converted  by  nitric  acid  into  the  oxide  (GeO2), 
and  weighed  as  such. 

Separation.  Germanium  may  be  separated  from  most  of 
the  elements  by  the  formation  of  a  soluble  sulpho  salt  with 
ammonium  sulphide;  when  the  solution  is  acidified  the 
sulphide  is  precipitated.  Germanium  may  be  separated 
from  arsenic,  antimony,  and  tin  as  follows:  the  solution  of 
the  sulpho  salts  is  exactly  neutralized  with  sulphuric  acid, 
allowed  to  stand  twelve  hours,  and  filtered;  the  filtrate  is 
evaporated  to  a  small  volume,  treated  with  ammonia  and 
sulphate  of  ammonium,  acidified  with  sulphuric  acid,  and 
saturated  with  hydrogen  sulphide.  Germanium  sulphide 
is  precipitated  (Truchot,  Les  Terres  Rares,  294). 

TITANIUM,  Ti,  48.1. 

Discovery.  In  the  year  1791  McGregor  (Crell  Annal.  (1791) 
i,  40,  103)  discovered  a  new  "metal"  in  a  magnetic  sand 
found  in  Menachan,  Cornwall.  This  sand  he  named  Mena- 
chinite,  and  the  newly  discovered  element  Menachite.  Four 
years  later  Klaproth  announced  the  discovery  of  a  new  earth 
in  a  rutile  which  he  was  engaged  in  studying  (Klapr.  Beitr. 
I,  233).  To  the  metal  of  this  earth  he  gave  the  name  Tita- 
nium, in  allusion  to  the  Titans.  In  1797,  however,  he 
found  that  titanium  was  identical  with  menachite  (Klapr. 
Beitr.  n,  236). 

Occurrence.     Titanium   is     found   combined   in    many 


TITANIUM.  59 

minerals,  but  never  in  considerable  quantity  in  any  one 
locality. 

Contains  TiO2 

Rutile,  TiO2 90-100% 

Dicksbergite,  vid.  Rutile 90-100% 

Brookite,  TiO2 '. 90-100% 

Octahedrite,  TiO2 90-100% 

Pseudobrookite,  Fe4(TiO4)3 44-  53% 

Perofskite,  CaTiO3 58-  59% 

llmenite,  FeTiO3 3-  59% 

Geikielite,  MgO -TiO2 67-68% 

Senaite,  (Fe,Pb)O •  2(Ti,Mn)O2 - 57-  58% 

Zirkelite,  (Ca,Fe)O-2(Zr,Ti,Th)O2 14-  15% 

Knopite,  R0-Ti02 54-  59% 

Derbylite,  6FeO-5TiO2-Sb2O5 34-  35% 

Lewisite,  sCaO - 2TiO2 •  3Sb2O5 n-  12% 

Mauzeliite,  4(Ca,Pb)O  -TiO2 - 2Sb2O5 7-     8% 

Titanite,  CaTiSiO5 34-42% 

Neptunite,  R2RTiSi4O12 i?-  i8% 

Hainite,  formula  doubtful undetermined 

Lamprophyllite,  formula  doubtful 

Keilhauite,  complex  silicate ' 26-  36% 

Schlormenite,  3CaO(Fe,Ti)2O3«3(Si,Ti)O2 12-  22% 

Guarinite,  CaTiSiO5 33-  34% 

Tscheffkinite,  complex  silicates 16-21% 

Astrophyllite,  (Na,K)4(Fe,Mn)4Ti(SiO4)4 7-  14% 

Johnstrupite,  complex  silicates 7-     8% 

Mosandrite,                         "       5-  10% 

Rinkite,                               "       13-  14% 

Dysanalyte,  6(Ca,Fe)TiO3-  (Ca,Fe)Nb2Ofl 40-  59% 

Pyrochlore,  RNb2Oe-R(Ti,Th)O3, 5-  14% 

in  in 

^schynite,  R2Nb4O13-R2(Ti,Th)5O13 21-  22% 

Polymignite,  sRTiO3-5RZrO3-R(Nb,Ta)2O6 18-  19% 


60  THE  RARER  ELEMENTS. 

Contains  TiO2 

in                    in 
Euxenite,  R(NbO3)3-R2(TiO3)3-|H20 20-23% 

in                  in 
Polycrase,  R(NbO3)3-2R(TiO3)3-3H2O 25-  29% 

Titanium  has  been  found  also  in  sand  on  the  banks  of  the 
North  Sea,  in  some  mineral  waters,  in  certain  varieties  of 
coal,  in  meteorites,  and  by  means  of  the  spectroscope  it 
has  been  detected  in  the  atmosphere  of  the  sun.  It  has 
been  found  in  the  ash  of  oak,  apple,  and  pear  wood,  in 
cow  peas,  in  cotton-seed  meal,  and  in  the  bones  of  men 
and  animals.  Vid.  also  Baskerville,  Jour.  Amer.  Chem. 
Soc.  xxi,  1099. 

Extraction.      Titanium    salts    may   be    extracted    from 
rutile  by  the  following  methods: 

(1)  The  mineral  is  fused  with  three  parts  of  a  mixture 
of  sodium  and  potassium  carbonates  and  the  fused  mass 
is  extracted  with  water.     The  titanium,  as  a  sodium  or 
potassium  titanate,  remains,  together  with  some  tin  and 
iron,  in  the  insoluble  residue.     This  mass  is  treated  with 
strong  hydrochloric  acid  until  dissolved.     The  solution  is 
then  diluted,  and  the  tin  is  removed  by  hydrogen  sulphide. 
The  sulphide  of  tin  is  filtered  off,  the  filtrate  is  made  am- 
moniacal  with  ammonium  hydroxide   and   again  treated 
with  hydrogen  sulphide.     The  iron  is  precipitated  as  the 
sulphide,  and  the  titanium  as  the  hydroxide.     After  filtra- 
tion the  precipitate  is  suspended  in  water  and  a  current 
of  sulphur  dioxide  is  passed  through  until  the  black  sul- 
phide of  iron  has  dissolved,  leaving  the  oxide  of  titanium. 

(2)  The  mineral  is  fused  with  three  parts  of  acid  potas- 
sium fluoride  and  the  fused  mass  is  extracted  with  hot  water 
and  a  little  hydrofluoric  acid.     The  titanium  separates,  on 
cooling,  as  the  potassium  fluotitanate  (K2TiF6  +  H20). 

(3)  The  mineral  is  fused  with  six  parts  of  acid  potassium 
sulphate  (vid.  Experiment  63). 

The  Element.     A.  Preparation.     Elementary  titanium 


TITANIUM.  6 1 

may  be  obtained  (i)  by  heating  potassium  fluotitanate 
with  potassium  (Berzelius  and  Wohler) ;  (2)  by  passing 
the  vapor  of  the  chloride  (TiCl4)  through  a  bulb  tube  con- 
taining sodium. 

B.  Properties.  As  prepared  in  the  laboratory,  tita- 
nium is  a  dark-gray  powder.  It  does  not  decompose  water 
at  ordinary  temperatures  and  acts  on  heated  water  but 
slightly.  When  heated  in  the  air  it  combines  with  the 
oxygen,  burning  brightly  to  the  oxide  (TiO2) ;  in  oxygen 
the  combination  is  accompanied  with  brilliant  light.  Ti- 
tanium is  readily  soluble  in  warm  hydrochloric  acid,  and 
is  attacked  by  dilute  hydrofluoric,  nitric,  sulphuric,  and 
acetic  acids.  It  combines  with  chlorine.  It  combines  also 
with  nitrogen,  forming  nitrides. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  titanium: 

Oxides .  .  .  TiO ;  (Ti3O4) ;  Ti2O3 ;  (Tipj  ;  TiO2 ;  (Ti2O5) ;  TiO3 

Hydroxides  Ti(OH)4        Ti(OH)6 

Chlorides  . .  Ti^                  TiCl4 

Bromide...  TiBr4 

Iodide TiI4 

Fluoride  . . .  TiF4 
Titanofluor- 

ides R2TiF6,  etc. 

Sulphides  .  .  Ti2S3                    TiS2 

Nitrides. . ..  Ti3N4 ;  Ti5N6 ;  TiN2 

Carbide ....  TiC 

Titanates. .  .  RTiO3;  R2TiO3 

Acids  (vid.  Hydroxides) .  . .  H2TiO3 

B.  Characteristics.  Although  a  number  of  oxides  of 
titanium  are  known,  the  dioxide  is  the  form  generally 
found,  and  the  salts  of  that  type  are  by  far  the  most  numer- 
ous and  important.  The  oxide  (TiO2)  resembles  the  oxide 
of  zirconium  (ZrO2)  in  acting  as  a  weak  base.  It  forms 


62  THE  RARER  ELEMENTS. 

salts  with  the  strong  acids,  but  does  not  combine  with  the 

weak  acids.     It  unites  with  the  strong  bases  to  form  tita- 

ii  i 

nates,   (RTiO3  and  R2TiO3).     It  has  less  basic  and  more 

acidic  properties  than  the  oxide  of  zirconium.  The  tet- 
rachloride  is  a  colorless  liquid  which  fumes  in  the  air. 
Titanium,  in  its  behavior  toward  reagents,  resembles  quite 
closely  both  niobium  and  tantalum,  with  which  it  is  often 
found  associated  (vid.  Occurrence). 

Estimation.  A.  Gravimetric.  Titanium  is  usually  pre- 
cipitated as  the  acid,  either  by  ammonium  hydroxide 
or  by  boiling  a  dilute  solution  acidified  with  acetic  or 
sulphuric  acid;  the  precipitate  is  ignited  and  the  element 
is  determined  as  the  oxide  (TiO2). 

B.  Volumetric.  Titanium  is  estimated  volumetrically 
(i)  by  treating  with  hydrogen  dioxide  a  definite  amount 
of  the  titanium  solution  to  be  determined  and  com- 
paring its  color  with  that  of  a  definite  amount  of  a 
standard  solution  of  titanium  similarly  treated  (Weller, 
Ber.  Dtsch.  chem.  Ges.  xv,  2592);  (2)  by  reducing  the 
titanium  from  the  dioxide  to  the  sesquioxide  condition, 
by  the  use  of  zinc  and  hydrochloric  acid,  and  then  oxidiz- 
ing it  with  permanganate  (Osborn,  Amer.  Jour.  Sci.  [3] 
xxx,  329). 

Separation.  The  general  method  for  the  separation 
of  titanium  from  the  other  members  of  the  aluminum 
group  is  to  boil  dilute  acidified  solutions  (vid.  Gravimetric 
Estimation).  The  titanium  precipitate,  however,  carries 
down  traces  of  other  elements,  as  aluminum  and  iron. 

From  iron  titanium  may  be  separated  (i)  by  passing 
hydrogen  sulphide  into  an  alkaline  solution  to  which  am- 
monium tartrate  has  been  added, — the  iron  sulphide  being 
precipitated  (Gooch,  Amer.  Chem.  Jour,  vn,  283) ;  (2)  by 
treating  a  mixture  of  ferrous  sulphide  and  titanic  acid 
with  sulphur  dioxide  (vid.  Extraction) ;  (3)  by  boiling  a 
neutral  solution  with  hydrogen  dioxide, — metatitanic  acid 


EXPERIMENTAL   WORK  ON   TITANIUM.  63 

being  precipitated;  (4)  by  treating  a  solution  of  the  salts 
with  phenylhydrazine, — titanic  acid  being  precipitated 
(Allen,  Jour.  Amer.  Chem.  Soc.  xxv,  421). 

From  aluminum  titanium  may  be  separated  by  boiling 
a  solution  containing  them,  in  the  presence  of  an  alkali 
acetate  and  of  acetic  acid  to  about  seven  per  cent,  of  the 
whole  solution, — titanium  basic  acetate  being  precipitated 
(Gooch,  Amer.  Chem.  Jour,  vn,  283). 

From  cerium  and  thorium  titanium  may  be  separated  by 
precipitating  the  double  sulphates  of  those  elements  with 
potassium  sulphate.  Methods  for  the  separation  from 
zirconium  have  already  been  given  (vid.  Zirconium) .  From 
niobium  and  tantalum  titanium  may  be  separated  by 
repeated  fusions  with  acid  potassium  sulphate  and  extrac- 
tions  of  the  melt  with  water, — the  titanium  being  in  soluble 
form. 

EXPERIMENTAL  WORK  ON  TITANIUM. 

Experiment  63.  Extraction  of  titanium  salts  from  rutile. 
(a)  Mix  5  grm.  of  finely  powdered  mineral  with  about  30  grm. 
of  acid  potassium  sulphate  and  fuse  until  the  mass  is  free 
from  black  particles.  Pulverize  the  fused  mass  and  ex- 
tract with  cold  water,  stirring  frequently  until  solution 
is  complete.  Add  ammonium  sulphide,  filter  and  wash. 
Suspend  the  precipitate,  which  consists  mainly  of  titanium 
hydroxide  and  ferrous  sulphide,  in  water  and  pass  a  cur- 
rent of  sulphur  dioxide  through  the  liquid  until  the  ferrous 
sulphide  has  dissolved,  as  shown  by  the  disappearance 
of  the  dark  color.  Filter,  and  wash  the  titanium  hydroxide 
which  remains. 

(b)  Alternative  method.  After  having  dissolved  the  fused 
mass  in  cold  water  (vid.  (a))  add  about  20  grm.  of  tartaric  acid 
to  hold  up  the  titanium  hydroxide,  and  make  the  solution 
faintly  ammoniacal.  Pass  hydrogen  sulphide  through  until 
the  ferrous  sulphide  is  completely  thrown  down.  Filter,  add 


64  THE  RARER  ELEMENTS. 

about  10  cm.3  of  concentrated  sulphuric  acid  to  the  filtrate, 
and  evaporate  in  a  porcelain  dish  under  a  draught  hood 
until  the  tartaric  acid  is  thoroughly  carbonized.  Allow 
the  mass  to  stand  until  cool,  add  water,  keeping  the  liquid 
cool  to  prevent  the  precipitation  of  the  titanium  hydroxide, 
and  decant  from  the  carbon  residue.  Filter  the  brown 
liquid  through  animal  charcoal  that  is  free  from  phos- 
phates and  precipitate  the  titanium  hydroxide  with  am- 
monium hydroxide  (R.  G.  Van  Name). 

Experiment  64.  Precipitation  of  titanium  hydroxide, 
(Ti(OH)4).  (a)  To  a  solution  containing  titanium  add 
sodium,  potassium,  or  ammonium  hydroxide.  Note  the 
comparative  insolubility  in  excess,  especially  in  ammo- 
nium hydroxide. 

(b)  Repeat  the  experiment,  using  the  alkali  carbonates. 
The  precipitate  is  the  same  as  in  (a). 

(c)  Note  the  solubility  of  the  freshly  precipitated  hy- 
droxide in  the  common  acids. 

(d)  Ignite  a  portion  of  the  precipitate  and  try  its  solu- 
bility in  acids. 

Experiment  65.  Precipitation  of  titanic  hydroxide  or 
acid  by  boiling.  (a)  Boil  a  dilute  acid  solution  of  titanic 
hydroxide.  Note  the  precipitation.  Filter,  and  test  the 
filtrate  with  ammonium  hydroxide. 

(b)  To  a  solution  of  titanic  acid  containing  enough 
free  acid  to  prevent  precipitation  on  boiling,  add  ammo- 
nium acetate.  Try  similarly  sodium  thiosulphate. 

Experiment  66.  Color  tests  of  solutions  containing 
titanium,  (a)  To  an  acid  solution  containing  titanium 
add  hydrogen  dioxide.  Note  the  yellow  color  (TiO3  in 
solution). 

(b)  To  a  solution  containing  titanium  add  a  piece  of 
metallic  zinc  and  enough  acid  to  start  the  action.      Note 
the  violet  color  which  develops. 

(c)  To   three   portions   of    dry  titanium   oxide   (Ti02) 


NIOBIUM  (COLUMBIUM};   TANTALUM.  65 

or  double  fluoride  (K2TiF6)  add  a  few  drops  of  strong 
sulphuric  acid.  Bring  into  contact  with  the  first  a  few 
particles  of  tannic  acid,  with  the  second  a  little  dry  pyro- 
gallic  acid,  and  with  the  third  some  morphia.  Note  the 
red  color. 

Experiment  67.  Negative  test  of  titanium  compounds. 
Pass  hydrogen  sulphide  through  a  solution  containing 
titanium.  Note  the  absence  of  precipitation. 

NIOBIUM  (COLUMBIUM),  Nb(Cb),  94;  TANTALUM,  Ta,  183. 

Discovery.  Hate  he  tt,  while  working  with  some  chro- 
mium minerals  in  the  British  Museum  in  1801,  came  across 
a  black  mineral  very  similar  to  those  upon  which  he  was 
engaged  (Phil.  Trans.  Roy.  Soc.  (1802),  49).  He  obtained 
permission  to  examine  it  and  found  it  to  consist  almost 
wholly  of  iron  and  an  earth  which  did  not  conform  to 
any  known  test.  He  described  it  as  "a  white,  tasteless 
earth,  insoluble  in  hot  and  cold  water,  acid  to  litmus, 
infusible  before  the  blowpipe,  and  not  dissolved  by  borax. ' ' 
The  only  acid  which  dissolved  it  was  sulphuric.  Since 
the  mineral  was  of  American  origin,  coming  from  Con- 
necticut, the  discoverer  named  it  Columbite,  and  the 
element  Columbium. 

About  a  year  later  Ekeberg  (Crell  Annal.  (1803)  i,  3), 
while  investigating  a  mineral  from  Kimito,  Finland,  which 
closely  resembled  columbite,  discovered  a  "metal"  which 
resembled  tin,  tungsten,  and  titanium.  It  proved  to  be 
none  of  these,  but  in  fact  a  new  element.  He  named  it 
Tantalum,  ' '  because  even  when  in  the  midst  of  acid  it 
was  unable  to  take  the  liquid  to  itself. ' '  Indeed,  insolu- 
bility in  acid  seemed  to  be  the  chief  characteristic  of  the 
new  substance. 

The  apparent  similarity  of  columbium  and  tantalum 
suggested  that  they  might  be  identical,  and  in  order  to 


66  THE  R4RER  ELEMENTS. 

solve  this  problem  Wollaston  (Phil.  Trans.  Roy.  Soa 
xcix,  246)  in  1809  began  to  work  on  tantalite  and  a  speci- 
men of  the  same  columbite  that  Hatchett  had  examined. 
He  found  that  the  freshly  precipitated  acids  were  both 
soluble  in  concentrated  mineral  acids;  if  they  were  dried 
it  was  necessary  to  fuse  them  both  with  caustic  alkalies 
before  they  could  be  dissolved.  Both  were  held  up  if 
ammonium  hydroxide  was  added  in  the  presence  of  citric, 
tartaric,  or  oxalic  acid.  Having  found  practically  the  same 
reactions  with  both  acids,  he  concluded  that  the  elementary 
substances  were  the  same.  The  specific  gravity  of  tantalite, 
however,  was  7.95,  and  that  of  columbite  5.91.  This  he 
explained  by  suggesting  different  conditions  of  oxidation 
or  different  states  of  molecular  structure.  These  con- 
clusions were  accepted,  and  for  many  years  the  element 
was  called  indifferently  tantalum  and  columbium. 

In  1844  Rose  began  to  investigate  the  same  subject. 
His  work  on  the  columbites  of  Bodenmais  and  Finland 
led  him  to  the  belief  that  there  were  two  distinct  acids 
in  the  columbite  from  Bodenmais,  one  similar  to  that  in 
tantalite,  the  other  containing  a  new  element,  to  which 
he  gave  the  name  Niobium,  from  Niobe,  daughter  of  Tan- 
talus. Though  niobium  proved  to  be  Hatchett 's  colum- 
bium, Rose's  name  for  the  element  has  been  the  one  more 
generally  adopted. 

Occurrence.  Niobium  and  tantalum  are  found,  each 
in  combination,  in  various  rare  minerals.  They  usually, 
though  not  invariably,  occur  together. 

Corttains 
Nb205 

Pyrochlore,  RNb2O6-R(Ti,Th)O3 47~58% 

Koppite,  R2Nb2O7  •  fNaF.  .  . , 61-62  % 

Hatchettolite, 

2R(Nb/ra)aOfl.Ra(Nb,Ta)207 63-67%* 

*Nb205+Ta206- 


NIOBIUM  (COLUMBIUM);   TANTALUM.  67 

Contains 
Nb205  Ta205 

Microlite,  Ca2Ta2O7 7-8%  68-69% 

Fergusonite,  (Y,Er,Ce)(Nb,Ta)O4 14-46%     4~43% 

in 
Sipylite,  RNbO4 47~48%     i-  2% 

Columbite,  (Fe,Mn)(Nb,Ta)2O6. .  26-77%     i~77% 

Tantalite,  FeTa2O6 3-40%  42-84% 

Skogbolite,      '-1       , 3-40%  42-84% 

Tapiolite,  Fe(Nb,Ta)2O6 11-12%  73~74% 

Mossite,  Fe(Nb,Ta)2O6.  . 83%* 


'2 
II  III 


Yttrotantalite,  RR2(Ta,Nb)4O15. 12-13%  46-47% 

in  ii 
Samarskite,  R2R3(Nb,Ta)6O21 41-56%  14-18% 

Stibiotantalite,  Sb2O3(Ta',Nb)2O5? 7  -  5   %         ji% 

o 

Annerodite,  complex 48-49% 

Hielmite,  complex.  .  . 4-16%  55-72% 

in  in 

^schynite,  R,Nb4Olt.R,(Ti,Th)Ai 32-33%  21-22% 

Polymignite, 

5RTiO3-5RZr03.R(Nb,Ta)2O6 11-12%     i-  2% 

in  in 

Euxenite,  R(NbO3)3-R2(TiO3)3-|H20 18-35% 

in  in 

Polycrase,  R(NbO3)3-2R2(TiO3)3.3H2O.  .  .    19-25%     o-  4% 

Wohlerite,  i2R(Si,Zr)O3-RNb2O6 12-14% 

Lavenite,  R(Si,Zr)O3  •  Zr(SiO3)2  •  RTa2O6.  .     o-  5 %* 

Dysanalyte,  6RTiO3-RNb2O6 0-23%     o-  5% 

Eucolite,  complex,  silicates 2-  4%* 

Melanocerite,  complex  silicates 3-  4% 

Tritomite,  complex  silicates I-  3% 

Cassiterite  (ainalite),  SnO2 o-  9% 

Extraction.  Salts  of  niobium  and  tantalum  may  be 
extracted  from  columbite  or  tantalite  by  either  of  the  fol- 
lowing methods: 

*  Nb205+Ta205. 


68  THE  RARER  ELEMENTS. 

(1)  The  mineral  is  fused  with  six  parts  of  potassium 
bisulphate,  the  fused  mass  is  pulverized  and  treated  with 
hot  water  and  dilute  hydrochloric  acid.     The  residue  is 
then  digested  with  ammonium  sulphide  to  remove  tin,  tung- 
sten, etc.,  and  again  warmed  with  dilute  hydrochloric  acid. 
After  this  treatment  it  is  washed  thoroughly  with  water 
and  dissolved  in  hydrofluoric  acid.     Filtration  is  followed 
by  the  addition  of  potassium  carbonate  to  the  clear  solu- 
tion until  a  precipitate  begins  to  form.     The  potassium 
and  tantalum   double   fluoride   separates   first  in  needle- 
like   crystals,  after  which  the   niobium  oxyfluoride   crys- 
tallizes in  plates. 

(2)  The  mineral  is  fused  with  three  parts  of  acid  potas- 
sium fluoride  (vid.  Experiment  68). 

The  Elements.  I.  NIOBIUM.  -A.  Preparation.  The  ele- 
ment niobium  may  be  obtained  by  reducing  the  chloride 
with  hydrogen  at  a  high  temperature  (Bloomstrand). 

B.  Properties.  Niobium  is  a  metallic  element  of 
steel-gray  color  and  brilliant  luster.  Heated  in  the  air 
it  ignites;  heated  in  chlorine  it  forms  the  chloride  (NbCl5). 
It  is  very  slightly  soluble  in  hydrochloric  acid,  nitric  acid, 
and  aqua  regia,  but  dissolves  in  concentrated  sulphuric  acid 
upon  the  application  of  heat.  Its  specific  gravity  is  7.06. 

II.  TANTALUM.  A.  Preparation.  Elementary  tanta- 
lum may  be  obtained  by  heating  the  potassium  and 
tantalum  fluoride  (K2TaF7)  with  potassium  and  extract- 
ing the  potassium  fluoride  with  water. 

B.  Properties.  Tantalum  in  the  elementary  condition 
is  a  black  substance  with  a  metallic  luster.  Like  niobium 
it  ignites  when  heated  in  the  air  and  forms  the  chloride, 
(TaCl5),  when  heated  in  chlorine.  It  is  insoluble  in  hydro- 
chloric, nitric,  and  sulphuric  acids,  and  in  aqua  regia,  but 
dissolves  in  hydrofluoric  acid.  Its  specific  gravity  is  10.78. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  niobium  and  tantalum: 


NIOBIUM  (COLUMBIUM);   TANTALUM.  69 

Oxides  ..........     Nb,O2 

Nb2O4  Ta2O4 

Nb206  Ta20, 

Chlorides  ........     NbCl3 

NbCl5  Tad. 

Oxychloride  .....     NbOCl, 

Bromides  .......     NbBr5  ,   TaBr5 

Oxybromide.  .  .  .     NbOBr, 

Fluorides  .......     NbF6  TaF8 

Oxyfluoride  .....     NbOF3 

Fluotantalates  .  .  K,TaF7 

Na2TaF7 
(NH4)2TaF7 
Double  fluorides  . 


Sulphide  ........  Ta2S4 

Oxysulphide.  .  .  .     Nb2OS3 

Nitride  .........  TasN, 

Niobates  ........     K8Nb6O19  +  i6H2O 

K6Nb4013  +  i3H20 

2K2Nb4Ou 

K4Nb2O7  + 

NalflNb14043 

Na2Nb2O6,  etc. 

Tantalates  ......  Of  types  R8Ta6O19  and  RTaO3, 

with  Na,  K,  NH4,  Ba,  and  Mg. 

B.  Characteristics.  The  compounds  of  niobium  closely 
resemble  those  of  tantalum,  both  in  chemical  form  and  in 
behavior  toward  reagents.  The  two  elements  are  closely 
associated  in  minerals  (vid.  Occurrence)  .  The  lower  oxides 
of  niobium  are  dark  powders  which  oxidize  when  heated. 
The  dioxide  is  soluble  in  hydrochloric  acid,  while  the  tetrox- 
ide  is  not  attacked  by  acids.  The  pentoxide  is  a  yellowish- 
white  amorphous  powder  somewhat  soluble  in  concen- 
trated sulphuric  acid  before  ignition,  but  insoluble  after. 


70  THE  RARER  ELEMENTS. 

Niobium  pentachloride  is  a  yellow  crystalline  substance 
which  tends  to  form  the  oxychloride  in  the  presence  of 
water,  and  is  reduced  to  the  trichloride  when  its  vapor  is 
passed  through  a  red-hot  tube.  The  fluoride  is  formed  by 
the  action  of  hydrofluoric  acid  upon  the  pentoxide. 

Tantalum  tetroxide  is  a  very  hard,  dark-gray,  porous 
mass  which  is  not  attacked  by  acids.  When  heated  it 
goes  over  to  the  higher  oxide.  The  pentoxide  of  tanta- 
lum is  a  white  powder  which  is  somewhat  soluble  in  acids. 
The  chloride  and  fluoride  of  tantalum  are  formed  similarly 
to  the  corresponding  salts  of  niobium  and  resemble  them 
in  general  behavior.  Niobates  and  tantalates  are  obtained 
by  fusing  the  oxides  with  caustic  alkalies;  these  salts  are 
soluble.  The  tantalum  compounds  give  no  color  test  with 
morphia,  tannic  acid,  or  pyrogallic  acid. 

Estimation.  A.  Gravimetric.  Niobium  and  tantalum 
are  ordinarily  weighed  as  the  oxides  Nb2O5  and  Ta2O5, 
obtained  from  ignition  of  the  acids. 

B.  Volumetric.  Niobium  may  be  estimated  volume t- 
rically  by  reduction  from  the  condition  of  the  pentoxide  to 
that  of  the  trioxide  by  means  of  zinc  and  hydrochloric 
acid  in  a  current  of  carbon  dioxide,  and  oxidation  with 
permanganate  (Osborn,  Amer.  Jour.  Sci.  [3]  xxx,  329). 

Separation.  The  method  usually  employed  for  the 
separation  of  niobium  and  tantalum  from  the  elements 
with  which  they  are  generally  associated — namely,  tita- 
nium, zirconium,  and  thorium — is  that  of  fusion  with  acid 
potassium  sulphate  (vid.  Titanium).  From  tin  and  tung- 
sten they  may  be  separated  by  ammonium  sulphide. 

The  separation  of  niobium  from  tantalum  is  one  of 
the  most  difficult  of  analytical  problems.  Marignac's 
method  (Ann.  Chim.  Phys.  [4]  viu,  i),  based  upon  the 

difference   in   solubility*  between  the  tantalum-potassium 

— 1 

*K2TaF7  is  soluble  in  151-157  parts  of  cold  water.  2KF  •  NbOF3+ H2O 
is  soluble  in  12-13  parts  of  cold  water. 


EXPERIMENTAL   WORK  ON  NIOBIUM  AND   TANTALUM.       7 1 

fluoride  (K2TaF7)  and  the  niobium-potassium  oxy fluoride 
(2KF-NbOF3  +  H2O),  is  the  most  satisfactory  known. 

EXPERIMENTAL    WORK    ON    NIOBIUM    AND 
TANTALUM. 

Experiment  68.  Extraction  of  niobium  and  tantalum 
salts  from  cohtmbite  or  tantalite.  Mix  5  grm.  of  the  finely 
ground  mineral  with  15  grm.  of  acid  potassium  fluoride 
and  fuse  thoroughly.  Pulverize  the  fused  mass  and  extract 
with  boiling  water  containing  a  little  hydrofluoric  acid. 
Evaporate  to  about  200  cm.3  and  allow  the  liquid  to  stand. 
The  potassium  and  tantalum  fluoride  separates  first  in 
needle-like  form;  the  niobium  and  potassium  oxyfluoride 
crystallizes  in  plates  on  concentration  of  the  solution. 
The  salts  of  the  two  elements  should  be  purified  as  far  as 
possible  by  fractional  crystallizations. 

Experiment  69.  Preparation  of  niobic  and  tantalic 
oxides  (acids),  (Nb2O5;  Ta2O5).  (a)  Evaporate  a  solution 
of  potassium  and  niobium  oxyfluoride  to  dryness,  add  strong 
sulphuric  acid,  and  heat  until  all  the  hydrofluoric  acid 
is  expelled  and  a  solution  is  obtained.  Cool  the  solution, 
dilute  with  water,  and  boil.  Niobic  acid,  (Nb2O5),  is  pre- 
cipitated. Filter,  and  test  the  filtrate  with  ammonium 
hydroxide. 

(6)  Repeat  the  experiment,  using  a  solution  of  potas- 
sium and  tantalum  fluoride  instead  of  the  niobium  salt. 

(c)  Test  the  action  of  alkali  hydroxides  or  carbonates 
in  excess  upon  solutions  of  niobium  and  tantalum  obtained 
in  (a)  and  (b). 

Experiment  70.  Action  of  fusion  with  sodium  or  potas- 
sium hydroxide  upon  niobic  and  tantalic  acids,  (a)  Melt 
a  gram  of  sodium  or  potassium  hydroxide  in  a  hard  glass 
tube,  add  a  small  quantity  of  dry  niobic  acid,  and  heat 
again.  Note  that  the  fused  mass  is  soluble  in  water. 


72  THE  RARER  ELEMENTS. 

(b)  Repeat    the    experiment,  using   dry   tantalic   acid 
instead  of  niobic. 

(c)  Acidify  portions  of  the  solutions  obtained  in   (a) 
and  (b). 

Experiment  71.  Color  tests  for  niobium,  (a)  Treat 
separate  portions  of  dry  niobic  oxide  (or  acid)  with  tannic 
acid,  pyrogallic  acid,  and  morphia,  as  in  Experiment  66  (c). 
Note  the  brown  color. 

(6)  Repeat  the  experiment,  using  tantalic  oxide  instead 
of  niobic.  Note  the  absence  of  color. 

(c)  Try  the  action  of  metallic  zinc  upon  an  acid  solu- 
tion containing  niobium. 

Experiment  72.  Negative  tests  of  niobium  and  tantalum. 
Note  that  hydrogen  sulphide  gives  no  precipitate,  and 
that  hydrogen  peroxide  gives  no  yellow  color  with  acid 
solutions  containing  niobium  or  tantalum. 

INDIUM,  In,    114. 

Discovery.  Indium  was  discovered  by  Reich  and 
Richter  in  1863,  in  the  course  of  an  examination  of  two 
ores  consisting  mainly  of  the  sulphides  of  arsenic,  zinc, 
and  lead  (J.  pr.  Chem.  LXXXIX,  441).  These  ores  had  been 
freed  from  the  greater  part  of  their  arsenic  and  sulphur 
by  roasting,  and  the  residue  had  been  evaporated  to  dry- 
ness  with  hydrochloric  acid  and  distilled.  The  crude 
chloride  of  zinc  thus  obtained  was  examined  with  the 
spectroscope  for  thallium,  since  the  presence  of  that  element 
had  been  indicated  in  similar  ores  from  the  Freiberg  mines. 
Instead  of  the  thallium  line,  however,  appeared  one  of 
indigo  blue  never  before  observed.  The  color  suggested 
the  name  Indium  for  the  unknown  element  present. 

Occurrence.  Indium  occurs  in  very  small  amounts, 
combined  with  sulphur,  in  many  zinc-blendes.  It  has  been 
found  in  zinc-blende  from  Freiberg  and  Breitenbrun  in 


INDIUM.  73 

Saxony,  and  from  Schonfeld  in  Bohemia ;  in  christophite,  a 
variety  of  zinc-blende;  in  zinc  prepared  from  these  ores; 
and  in  the  flue-dust  from  ovens  used  for  roasting  zinc  ores. 
It  has  also  been  found  in  wolframite  from  Zinnwald.  The 
proportion  of  indium  in  the  minerals  named  varies  from 
one  tenth  of  one  per  cent,  to  mere  traces.  Lockyer  de- 
tected it  in  the  atmosphere  of  the  sun.  Hartley  and  Ra- 
mage  (Jour.  London  Chem.  Soc.  (1897),  533,  547)  have  dis- 
covered it  spectroscopically  in  many  iron  ores, — notably 
siderites, — in  some  manganese  ores,  in  zinc-blendes,  in 
five  tin  ores  examined,  and  in  many  pyrites. 

Extraction.  Indium  salts  may  be  obtained  as  follows 
from  zinc  that  has  been  extracted  from  indium-bearing 
blendes.  The  crude  metal  is  nearly  dissolved  in  hydro- 
chloric or  nitric  acid,  and  the  solution  is  allowed  to  stand 
twenty-four  hours  with  the  undissolved  metal.  A  spongy 
mass,  consisting  of  the  indium  together  with  lead,  copper, 
cadmium,  tin,  arsenic,  and  iron,  collects  upon  the  residual 
zinc.  This  mass  is  washed  with  water  containing  some 
sulphuric  acid ;  it  is  then  dissolved  in  nitric  acid  and  evapo- 
rated with  sulphuric  acid  until  all  the  nitric  acid  is  removed. 
By  this  process  the  lead  is  precipitated,  and  it  may  be 
removed  by  filtration.  The  solution  that  remains  is  treated 
with  ammonium  hydroxide  in  excess,  and  the  hydroxides 
of  iron  and  indium  are  filtered  off  and  dissolved  in  a  small 
amount  of  hydrochloric  acid.  This  solution  is  treated 
with  an  excess  of  acid  sodium  sulphite  and  boiled.  In- 
dium is  precipitated  as  the  basic  sulphite  (In2(SO3)3  •  In2(OH)6 
+  5H20). 

The  Element.  A.  Preparation.  Elementary  indium 
may  be  obtained  (i)  by  heating  the  oxide  with  carbon 
or  in  a  current  of  hydrogen;  (2)  by  heating  the  oxide 
with  sodium  under  a  layer  of  dry  sodium  chloride ;  (3)  by 
treating  the  salts  with  zinc. 

B.    Properties.     Indium  is  a  soft  white  metal,  less  vola- 


74  THE  RARER  ELEMENTS. 

tile  than  cadmium  and  zinc.  It  melts  at  174°  C.  At 
ordinary  temperatures  it  is  very  stable  in  the  air,  but  when 
heated  it  ignites  and  burns  with  a  violet  flame  to  the 
oxide.  It  does  not  decompose  boiling  water.  It  dissolves 
easily  in  hydrochloric,  nitric,  and  sulphuric  acids.  Its 
specific  gravity  is  given  at  from  7.1  to  7.4. 

Compounds.     A.    Typical  forms.     The  following  com- 
pounds of  indium  are  known: 

Oxides  .............  InO    In2O3 

Hydroxide  ..........  In(OH), 

Chlorides  ...........   InCl  InCl2  InCl3 

Indium  -  hydrochloric 

acid  .............  H3InCl6 

Bromide  ...........  InBr3 

Iodide  ............  .  InI3 

Nitrate  ...........  .  In2(NO3)6  +  9H2O 

Sulphate  ..........  .  In2(SO4)3 

Double  sulphates  ____  In2(SO4)3  -  K2SO4  +  24H2O  ; 

In2(S04)3.(NH4)2S04  + 


Sulphite  ...........  ;:-  In2(S03)3  -  In2(OH)6  +  5H2O 

Sulphide  ..........  '.  In2S3 

Sulpho  salts  .........  K2In2S4  ;  Na2In2S4 

B.  Characteristics.  Indium  resembles  aluminum  in 
forming  alums  with  potassium  and  ammonium  sulphates, 
and  in  having  a  hydroxide  soluble  in  excess  of  potassium 
or  sodium  hydroxide.  It  resembles  zinc  in  forming  a 
sulphide  with  hydrogen  sulphide,  but  in  the  case  of  indium 
this  salt  is  yellow.  Indium  monoxide  is  a  dark  powder 
slowly  soluble  in  dilute  acids.  The  sesquioxide  is  a  yellow- 
ish-white powder  easily  soluble  in  warm  acid.  The  di- 
chloride  is  formed  directly  by  the  union  of  chlorine  with  the 
metal,  and  is  a  white,  crystalline  mass.  In  water  it  sepa- 
rates into  the  trichloride  and  the  metal.  By  fusion  of 


GALLIUM  75 


the  dichloride  with  elementary  indium  the  monochloride 
is  formed, — a  reddish-black,  crystalline  substance.  The 
trichloride  is  formed  also  by  the  action  of  chlorine  in  excess 
upon  the  metal ;  it  is  white  like  the  dichloride  and  dissolves 
in  water  with  the  evolution  of  heat.  Solutions  of  indium 
salts  color  the  flame  violet  and  give  a  characteristic  flame 
spectrum. 

Estimation.  Indium  is  generally  determined  as  the 
oxide,  (In2O3),  obtained  by  ignition  of  the  hydroxide,  or  as 
the  sulphide,  (In^g),  obtained  by  precipitation  with  hydro- 
gen sulphide  in  the  presence  of  sodium  acetate. 

Separation.  The  separation  of  this  very  rare  element 
from  those  elements  with  which  it  is  usually  associated 
is  treated  under  Extraction. 

GALLIUM,  Ga,   70. 

Discovery.  In  1875  Lecoq  de  Boisbaudran,  who  had 
done  much  work  with  spectrum  analysis,  notified  the 
Academic  des  Sciences  of  his  discovery  of  a  new  element 
in  a  zinc-blende  from  the  mine  of  Pierrefitte  in  the  Pyre- 
nees, and  proposed  for  it  the  name  Gallium  (Compt.  rend. 
LXXXI,  493;  Chem.  News  xxxn,  159).  The  individu- 
ality of  the  new  body  was  distinctly  indicated  by  the 
spectroscope,  but  so  small  was  the  amount  of  it  in  the 
possession  of  the  discoverer  that  few  of  its  reactions  were 
determined.  Among  the  properties  which  he  described, 
however,  were  the  following:  the  oxide,  or  perhaps  a  sub- 
salt,  was  thrown  down  by  metallic  zinc  in  a  solution  con- 
taining chlorides  and  sulphates;  in  a  mixture  containing 
an  excess  of  zinc  chloride  the  new  body  was  the  first  to 
be  precipitated  by  ammonia;  in  the  presence  of  zinc  it 
was  concentrated  in  the  first  sulphides  deposited;  the 
spark  spectrum  of  the  concentrated  chloride  showed  two 
violet  lines,  one  of  them  of  considerable  brilliance. 


76  THE  RARER  ELEMENTS. 

Occurrence.  Gallium  is  found  combined,  in  very  small 
amounts,  in  certain  minerals,  chiefly  zinc-blendes  from 
Bensberg  on  the  Rhine,  Pierrefitte,  and  other  localities. 
It  has  been  detected  in  some  American  zinc-blendes  (Chem. 
Ztg.  (1880),  443).  The  Bensberg  sphalerite,  one  of  the 
richest  sources,  contains  0.016  grm.  per  kilo. 

Hartley  and  Ramage  obtained  the  following  interesting 
results  by  means  of  the  spectroscope  (Jour.  London  Chem. 
Soc.  (1897),  533,  547) :  the  presence  of  gallium  was  indicated 
in  thirty -five  out  of  ninety -one  iron  ores  examined;  in  all 
the  magnetites,  seven  in  number;  in  all  the  aluminum 
ores,  fifteen  in  number,  mostly  kaolin  and  bauxite;  in 
four  out  of  twelve  manganese  ores;  and  in  twelve  out  of 
fourteen  zinc-blendes. 

Extraction.  Salts  of  gallium  are  obtained  by  the  fol- 
lowing process :  The  mineral  is  dissolved  in  aqua  regia  and 
the  excess  of  acid  expelled  by  boiling.  When  the  solution  is 
cold,  pure  zinc  is  added,  which  precipitates  the  antimony, 
arsenic,  bismuth,  copper,  cadmium,  gold,  lead,  mercury, 
silver,  tin,  selenium,  tellurium,  and  indium.  These  are 
filtered  off  while  there  is  still  some  evolution  of  hydrogen, 
and  the  filtrate  is  boiled  from  six  to  twenty-four  hours 
with  metallic  zinc.  Gallium  is  precipitated  as  a  basic 
salt,  together  with  salts  of  aluminum,  iron,  zinc,  etc.  To 
obtain  the  gallium  salt  in  a  more  nearly  pure  condition 
the  precipitate  is  dissolved  in  hydrochloric  acid,  the  solu- 
tion is  treated  with  hydrogen  sulphide,  and  after  filtra- 
tion and  the  removal  of  the  excess  of  hydrogen  sulphide 
by  boiling,  sodium  carbonate  is  added  in  small  portions. 
The  gallium  salt  is  the  first  to  be  precipitated,  and  the  pre- 
cipitates are  collected  as  long  as  they  show  the  gallium 
lines  in  the  spark  spectrum.  These  precipitates  are  dis- 
solved in  sulphuric  acid  and  the  solution  is  diluted  largely 
with  water  and  boiled.  The  basic  sulphate  of  gallium 
which  is  thus  thrown  down  is  dissolved  in  sulphuric  acid, 


GALLIUM.  77 

and  potassium  hydroxide  is  added  in  excess.  Iron  if 
present  is  removed  at  this  point  by  filtration  and  the 
gallium  oxide  is  then  precipitated  from  the  filtrate  by 
carbon  dioxide. 

The  Element.  A.  Preparation.  Gallium  in  the  elemen- 
tary condition  has  been  obtained  by  subjecting  an  alkaline 
solution  of  the  oxide  to  electrolysis. 

B.  Properties.  A  gray,  lustrous  metal,  showing  green- 
ish-blue lights  on  reflecting  surfaces,  gallium  is  malleable 
and  fairly  hard.  Its  fusing  point,  30.15°  C.,  is  so  low 
that  it  melts  readily  from  the  warmth  of  the  hand.  In 
water,  and  in  air  at  ordinary  temperatures,  it  is  unchanged ; 
when  heated  in  air  or  oxygen  it  is  oxidized  only  superfi- 
cially. It  combines  rapidly  with  chlorine,  more  slowly  with 
bromine,  and  not  at  all  with  iodine  unless  heat  is  applied. 
Gallium  is  soluble  in  hydrochloric  and  warm  nitric  acids, 
and  somewhat  soluble  in  potash  and  ammonia  solutions. 
It  alloys  easily  with  aluminum,  and  these  alloys  decompose 
cold  water  rapidly.  Its  specific  gravity  is  6. 

Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  gallium  are  known : 

Oxides GaO?  Ga2O3 

Hydroxide Ga(OH)3? 

Chlorides GaCl2  GaCl3 

Bromide GaBr3 

Iodide GaI3 

Nitrate Ga,(NO,)« 

Sulphate Ga2(SO4)3 

Double  sulphate Ga2(SO4)3  •  (NH4)2SO4  +  24H2O 

B.  Characteristics.  The  compounds  of  gallium  resem- 
ble those  of  aluminum  and  indium  in  forming  alums  and 
in  having  a  hydroxide  soluble  in  excess  of  sodium  or 
potassium  hydroxide.  The  salts  are  colorless,  and  in 
dilute  solutions  tend,  on  being  heated,  to  become  basic 


78  THE  RARER  ELEMENTS. 

and  separate  from  the  solution.  The  oxide  (Ga2O3)  is  in- 
soluble in  acids  and  alkalies  after  ignition. 

Estimation.  Gallium  is  usually  weighed  as  the  oxide 
(Ga203). 

Separation.*     Vid.  Extraction. 


THALLIUM,  Tl,  204.1. 

Discovery.  Some  years  previous  to  1861  Crookes  had 
been  engaged  in  the  extraction  of  selenium  from  a  selen- 
iferous  deposit  which  he  had  obtained  from  the  sulphuric- 
acid  manufactory  at  Tilkerode  in  the  Hartz  Mountains. 
Some  residues,  left  after  the  purification  of  the  selenium, 
and  supposed  to  contain  tellurium,  were  set  aside  and 
not  examined  until  1861,  when,  needing  tellurium,  Crookes 
vainly  tried  to  isolate  it  by  various  chemical  methods. 
At  length  he  resorted  to  spectrum  analysis  and  tested 
some  of  the  residue  in  the  flame.  The  spectrum  of  selen- 
ium appeared,  and  as  it  was  fading,  and  he  was  looking  for 
evidence  of  tellurium,  a  new  bright-green  line  flashed  into 
view.  The  element  whose  presence  was  thus  indicated 
received  the  name  Thallium,  from  the  Greek  6ct\Xost  or 
the  Latin  thallus,  a  budding  twig  (Chem.  News  in,  194). 

About  the  same  time  Lamy  announced  the  discovery 
of  the  same  element  (Ann.  Chim.  Phys.  [3]  LXVII,  385), 
but  after  much  discussion  and  the  presentation  of  much 
evidence  on  both  sides  it  was  declared  that  Crookes  had 
the  priority  of  discovery. 

Occurrence.  Thallium  occurs  in  certain  very  rare 
minerals : 

Crookesite,  (Cu,Tl,Ag)2Se,  contains  16-19%  Tl 
Lorandite,  TlAsS2,  "         59-60%  Tl 

*  For  a  detailed  study  of  the  separation  of  gallium,  see  many  articles  by 
Lecoq  de  Boisbaudran,  Compt.  rend,  xciv-xcvm. 


THALLIUM.  79 

It  is  found  also  in  very  small  quantities  in  berzelianite, 
(Cu2Se) ;  in  some  zinc-blendes  and  copper  pyrites ;  in  iron 
pyrites  from  Theux,  Namur,  Philippe ville,  Alais,  and  Nantes ; 
in  lepidolite  from  Mahren;  and  in  mica  from  Zinnwald. 
It  has  been  detected,  together  with  caesium,  rubidium,  and 
potassium,  in  the  mineral  waters  of  Nauheim  and  Orb. 
Its  presence  in  the  flue-dust  from  some  iron  furnaces  and 
sulphuric-acid  works,  as  well  as  in  some  crude  sulphuric 
and  hydrochloric  acids,  may  be  traced  to  its  presence  in 
the  pyrites  used. 

Extraction.  Thallium  salts  may  be  extracted  by  the 
following  methods: 

(1)  From  minerals.  The  finely  powdered  mineral  is  dis- 
solved in  aqua  regia.     The   solution  is  evaporated  with 
sulphuric  acid  until  the  free  acid  has  been  removed ;  it  is 
then    diluted    abundantly    with    water,    neutralized    with 
sodium  carbonate,    and   treated  with  potassium  cyanide 
in  excess.     This  precipitates  the  bismuth  and  lead,  which 
are   filtered   off.     The   filtrate   is   treated   with   hydrogen 
sulphide,  which  precipitates  the  cadmium,  mercury,  and 
thallium   as   the    sulphides.     Very   dilute    sulphuric   acid 
dissolves  the  thallium  sulphide,  leaving  the  cadmium  and 
mercury  sulphides  undissolved  (Crookes). 

(2)  From  flue-dust.      The  material  is  treated  with  an 
equal  weight  of  boiling  water  in  a  large  wooden  tub,  and  is 
allowed   to   stand   twenty-four   hours.     The   liquid   is   si- 
phoned off    and  is  precipitated  with  hydrochloric  acid.* 
The  crude  chloride  thus  obtained  is  treated  with  an  equal 
weight  of  sulphuric  acid,  and  heated  to  expel  the  hydro- 
chloric acid  and  the  greater  part  of  the  excess  of  sulphuric. 
The  sulphate  obtained  is  dissolved  in  water,  the  solution 
is  neutralized  with  chalk  and  filtered.      By  the  addition 
of  hydrochloric  acid  to  the  filtrate,  nearly  pure  thallous 
chloride  is  precipitated  (Chem.  News  vm,  159). 

*  Three  tons  of  dust  gave  sixty-eight  pounds  of  crude  thallous  chloride. 


8o 


THE  RARER  ELEMENTS. 


The  Element.  A.  Preparation.  The  element  thallium 
may  be  obtained  (i)  by  fusing  a  mixture  of  thallous  chloride 
and  sodium  carbonate  with  potassium  cyanide;  (2)  by 
submitting  the  carbonate  or  the  sulphate  to  electrolysis; 
(3)  by  heating  the  oxalate;  and  (4)  by  precipitating  with 
zinc  from  an  alkaline  solution  of  a  thallous  salt. 

B.  Properties.  Metallic  thallium  is  in  color  whitish 
to  blue  gray,  with  the  luster  of  lead.  It  is  soft  and  malle- 
able and  melts  at  285°  C.  It  oxidizes  readily  at  high 
temperatures,  but  is  not  acted  upon  by  water  free  from  air. 
It  is  soluble  in  dilute  nitric  and  sulphuric  acids.  It  is 
a  poor  conductor  of  electricity.  The  specific  gravity  of 
thallium  is  n.88. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  thallium: 

Oxides  ..........  T12O  T12OS 

Hydroxides  ......  T1OH  T1(OH)3 

Carbonate  .......  T12COS 

Chlorides  ........  T1C1  T1C13+  H2O 

Double  chlorides  .  .  T1C1  •  HgCl2  ;  3T1C1  •  Fed,  ;  T1C1,  -  3KC1+  2H2O  ;  etc. 

TlCl-AuCl,;  etc. 

Chlorate  .........  T1C1OS 

Perchlorate  ......  T1C1O4 

Bromides  ........  TIBr  TlBr, 

Double  bromides  .  .  TlBr3  •  KBr+  2H2O  ; 

TlBr8-3TlBr 

Bromate  .........  TIBrO, 

Iodides  ..........  Til  Til, 

Double  iodides  ----  Til  -  KI  T1I3  •  NH4I 

lodates  ..........  T1IOS  T1(IO3)8 

Periodate  ........  3T12O3  -  I2O7+  3oH2O 

Thiosulphate  .....  TlzS^ 

Sulphides  ........  T1,S  T12S3 

Sulphite  .........  TljSO, 

Sulphates  ........  TljSO,  ;  T1HSO4  Tl^SOJ, 

Double  sulphates  .  .  with  MgSO4,  ZnSO4,  CuSO4,  etc. 

Alums  ...........  T12S04-  A12(S04),+  24H2O; 

Tl2S(VFe2(S04)3+24H20 

Nitrates  ..........  T1NOS  T1(NO3)3+  4H2O 

Phosphates  .......  T13PO4;  T14P2O7;  T1PO,  T1PO4+  2H2O 


THALLIUM.  8 1 

Arseniates Tl8AsO4  Tl  AsO4+  2H2O 

Cyanides T1CN  T1(CN)3-T1CN 

Sulphocyanide T1SCN 

Ferrocyanide Tl4Fe(CN)8-f-  2H,O 

Silicofluoride TljSiF8 

Chromates Tl2CrO4;  Tl2Cr2OT 

Chloroplatinate  . . .  Tl2PtCl8  • 

Molybdate Tl2MoO4 

Tungstate T12WO4 

Vanadates T13VO4;  T14V2O7;  T1VO3 

B.  Characteristics.  Thallium  compounds  are  known 
in  two  conditions  of  oxidation,  the  thallous,  (T12O),  and 
the  thallic,  (T12O3) .  The  lower  condition  is  the  more  stable ; 
consequently  the  thallous  compounds  are  the  more  numer- 
ous and  the  better  known.  When  the  metal  is  allowed 
to  oxidize  in  the  air  it  forms  the  thallous  oxide,  but  when  it 
is  melted  in  an  atmosphere  of  oxygen,  thallic  oxide  is  ob- 
tained. Thallic  chloride,  bromide,  and  iodide  may  be 
formed  by  treating  the  corresponding  thallous  salts  with 
an  excess  of  chlorine,  bromine,  and  iodine,  respectively. 
In  general,  the  thallous  salts  may  be  oxidized  to  the  thallic 
form  by  strong  oxidizing  agents,  such  as  potassium  per- 
manganate, lead  dioxide,  barium  dioxide,  etc.  Thallium 
in  the  lower  condition  resembles  the  alkalies  potassium, 
caesium,  and  rubidium  in  having  a  soluble  hydroxide,  car- 
bonate, and  sulphate,  and  an  insoluble  chloroplatinate ; 
also  in  forming  alums.  It  resembles  lead  in  forming  an 
insoluble  sulphide  and  chromate,  and  in  having  halogen 
salts  soluble  in  hot  water.  The  thallous  salts  are  color- 
less when  the  base  is  combined  with  a  colorless  acid.  The 
sulphide  is  brownish  black.  The  thallic  salts  are  in  general 
unstable,  and  on  being  heated  with  water  tend  to  precipitate 
the  oxide  (T12O3-H20).  They  may  be  easily  reduced  to 
the  lower  condition  by  the  action  of  reducing  agents.  They 
may  be  formed  by  the  careful  treatment  of  thallic  oxide 
with  acids,  as  well  as  by  the  action  of  strong  oxidizing 
agents  upon  the  thallous  salts.  Solutions  of  thallium 


82  THE  RARER  ELEMENTS. 

salts  in  either  condition  of  oxidation  give  to  the  flame  a 
characteristic  green  color. 

Estimation.*  A.  Gravimetric.  Thallium  is  generally 
weighed  in  the  thallous  condition  (i)  as  the  chloroplati- 
nate,  (Tl2PtCl6),  after  precipitation  by  chloroplatinic  acid 
(Crookes,  Select  Methods,  Second  Edition,  380) ;  (2)  as  the 
iodide  (Til),  after  precipitation  by  potassium  iodide 
(Werther,  Zeitsch.  anal.  Chem.  in,  i,  and  J.  B.  (1864),  712; 
Long,  Zeitsch.  anal.  Chem.  xxx,  342) ;  (3)  as  the  chro- 
mate  (Tl2CrO4),  after  precipitation  in  alkaline  solution  by 
potassium  chromate  (Browning  and  Hutchins,  Amer. 
Jour.  Sci.  [4]  vin,  460);  (4)  as  the  sulphate  (T12SO4),  after 
evaporation  of  appropriate  salts  with  sulphuric  acid  in  ex- 
cess and  ignition  at  low  red  heat,  or  as  the  acid  sulphate, 
(T1HSO4),  obtained  by  substituting  for  ignition  heating  at 
220°-240°C.  (Browning,  Amer.  Jour.  Sci.  [4]  ix,  137). 

B.  Volumetric.  Thallium  is  estimated  volumetric- 
ally  (i)  by  the  oxidation  of  thallous  salts  with  perman- 
ganate (Crookes,  Select  Methods,  Second  Edition,  381); 
(2)  by  the  action  of  potassium  iodide  upon  thallic  salts, 
as  shown  in  the  following  equation  (Thomas,  Compt.  rend. 
cxxxiv,  655):  T1C13  +  3KI=T1I  +  3KC13  +  I2. 

Separation.!  In  the  more  stable  thallous  condition,  to 
which  thallic  salts  may  readily  be  reduced,  thallium  may 
be  separated  as  follows:  from  the  metals  which  give 
precipitates  with  hydrogen  sulphide  in  acid  (but  not  acetic) 
solution,  by  hydrogen  sulphide;  from  elements  which 
form  insoluble  hydroxides'  with  the  alkali  hydroxides,  by 
these  reagents;  and  from  the  alkalies  and  alkali  earths, 
by  ammonium  sulphide. 

*  See  also  Hebberling,  Liebig  Annal.  cxxxv,  207 ;  Phipson,  Compt. 
rend.  LXXVIII,  563;  Neumann,  Liebig  Annal.  ccxuv,  349;  Feit,  Zeitsch. 
anal.  Chem.  xxvin,  314;  Carnot,  Compt.  rend,  cix,  177;  Sponholz,  Zeitsch. 
anal.  Chem.  xxxi,  519;  Thomas,  Compt.  rend,  cxxx,  1316;  Marshall, 
Jour.  Soc.  Chem.  Ind.  xix,  994. 

t  See  Crookes,  Select  Methods,  Second  Edition,  382-386. 


EXPERIMENTAL   WORK  ON   THALLIUM.  83 

EXPERIMENTAL  WORK  ON  THALLIUM. 

Experiment  73.  Extraction  of  thallium  salts  from  flue- 
dust.  The  method  described  under  Extraction  may  be 
followed. 

Experiment  74.  Precipitation  of  thallous  chloride,  bro- 
mide, and  iodide  (T1C1;  TIBr;  Til),  (a)  To  a  solution  of 
a  thallous  salt  add  hydrochloric  acid  or  a  chloride  in  solu- 
tion. Note  the  solvent  action  of  boiling  water.  Try 
the  effect  of  cooling  the  hot  solution. 

(b)  Repeat  the  experiment,  using  potassium  bromide 
as  the  precipitant. 

(c)  Try  similarly  potassium  iodide. 

Experiment  75.  Precipitation  of  thallium  chloroplati- 
nate  (Tl2PtCl6).  To  a  solution  of  a  thallous  salt  add  a 
few  drops  of  a  solution  of  chloroplatinic  acid. 

Experiment  76.  Precipitation  of  thallous  chr ornate 
(Tl2CrO4).  To  a  solution  of  a  thallous  salt  add  some  potas- 
sium chromate  in  solution.  Try  the  action  of  acids  upon 
the  precipitate. 

Experiment  77.  Precipitation  of  thallous  sulphide  (T12S). 
(a)  Through  a  solution  of  a  thallous  salt  acidified  with 
dilute  sulphuric  acid  pass  hydrogen  sulphide.  Note  the 
absence  of  precipitation.  Divide  the  solution,  and  to  one 
part  add  ammonium  acetate  and  to  the  other  ammonium 
hydroxide. 

(b)  Try  the  action  of  ammonium  sulphide  upon  a  thal- 
lous salt  in  solution. 

Experiment  78.  Oxidation  of  thallous  salts,  (a)  To  a 
solution  of  a  thallous  salt  acidified  with  sulphuric  acid  add 
gradually  a  little  potassium  permanganate.  Note  the 
disappearance  of  the  color  of  the  permanganate. 

(b)  To  a  solution  of  a  thallous  salt  add  bromine  water 
until  the  color  of  the  bromine  ceases  to  fade.  To  one 
portion  add  a  few  drops  of  a  solution  of  a  chloride  or  bro- 


**4  THE  RARER  ELEMENTS. 

mide.  Note  the  absence  of  precipitation.  To  another 
portion  add  sodium  or  potassium  hydroxide.  Note  the 
precipitation  of  brown  thallic  hydroxide,  (T12O3-H2O). 

Experiment  79.  Reduction  of  a  thallic  salt.  To  a  solution 
of  a  thallic  salt  formed,  for  example,  as  in  Experiment 
78  (b)  add  stannous  chloride.  Note  the  precipitation 
of  thallous  chloride,  (T1C1). 

Experiment  So.  Flame  and  spectroscopic  tests  for  thal- 
lium salts,  (a)'  Dip  the  end  of  a  platinum  wire  into  a 
solution  of  a  thallium  salt  and  hold  it  in  the  flame  of  a 
Bunsen  burner.  Note  the  green  color. 

(b)  Examine  spectroscopically  the  flame  colored  by 
a  solution  of  a  thallium  salt.  Observe  the  green  line. 

Experiment  81.  Negative  tests  of  thallous  salts.  Note 
that  sulphuric  acid  and  the  alkali  hydroxides  and  car- 
bonates give  no  precipitate  with  solutions  of  thallous  salts. 

VANADIUM,  V,  51.2. 

Discovery.  As  early  as  1801  Del  Rio  announced  the 
discovery  of  a  new  metal  in  a  lead  ore  from  Zimapan, 
Mexico.  He  named  it  Erythronium  (epvQpos,  red),  be- 
cause its  salts  became  red  when  heated  with  acids 
(Annal.  der  Phys.  u.  Chem.  LXXI,  7).  Fourteen  years  later 
Collet  Descotils  examined  the  supposed  metal  and  pro- 
nounced it  an  impure  oxide  of  chromium, — a  conclusion 
that  Del  Rio  himself  came  to  accept  (Ann.  de  Chim.  LIII, 
268). 

In  1830  Sef strom  found  an  unknown  metal  in  an  iron 
ore  from  Taberg,  Sweden.  He  proposed  for  it  the  name 
Vanadium,  from  Vanadis,  the  Scandinavian  goddess  more 
commonly  known  as  Freia  (Amer.  Jour.  Sci.  [i]  xx,  386). 
Almost  immediately  Wohler  showed  the  identity  of  vana- 
dium with  the  metal  described  by  Del  Rio  (Pogg.  Annal. 
xxi,  49). 


VANADIUM.  85 

Occurrence.  Vanadium  is  found  quite  widely  distrib- 
uted, but  always  in  combination,  and  in  very  small  quan- 
tities: 

Contains 
V205. 

Vanadinite,  (PbCl)Pb4(VO4)3 8-21  % 

Descloizite,  (Pb,Zn)2(OH)VO4 20-22% 

Cuprodescloizite,  (Pb,Zn,Cu)2(OH)VO4 17-22% 

Calciovolborthite,  (Cu,Ca)2(OH)VO4 .'....  37~39% 

Carnotite,  K2O-2U2O3-V2O5-3H20 19-20% 

Brackebuschite,  formula  doubtful 24-25% 

Psittacinite,  formula  doubtful 17-26% 

Volborthite,                                14-15% 

Pucherite,  BiVO4 22-27% 

Roscoelite,  silicate,  formula  doubtful 21-29% 

Ardennite,       "  "  "        traces  -  9% 

Vanadium  has  been  detected  also  in  some  copper,  lead, 
and  iron  ores,  in  certain  clays  and  basalts,  and  sometimes 
in  soda  ash  and  phosphate  of  soda. 

Extraction.  Vanadium  salts  may  be  extracted  from 
mineral  sources  by  the  following  methods: 

(1)  The  mineral  is  fused  with  potassium  nitrate,  and 
.  the  potassium  vanadate  thus  formed  is  extracted  with  water. 

By  the  addition  of  a  soluble  lead  or  barium  salt  to  the 
solution  the  lead  or  barium  vanadate  is  precipitated.  This 
insoluble  vanadate  is  decomposed  by  means  of  sulphuric 
acid,  and  the  barium  or  lead  sulphate  is  filtered  off.  By 
saturation  of  the  filtrate  with  ammonium  chloride  the 
ammonium  vanadate  is  precipitated. 

(2)  The  finely  ground  mineral  is  decomposed  by  nitric 
acid  (vid.  Experiment  82). 

The  Element.  A.  Preparation.  Elementary  vanadium 
may  be  prepared  by  long  heating  of  the  dichloride  in  a  cur- 
rent of  hydrogen. 


86  THE  RARER  ELEMENTS. 

B.  Properties.  Vanadium  is  a  non-magnetic,  light- 
gray  powder,  somewhat  crystalline  in  appearance.  It 
oxidizes  slowly  in  the  air  at  ordinary  temperatures,  but 
more  rapidly  when  heated,  going  through  various  degrees 
of  oxidation  and  showing  a  characteristic  color  for  each 
oxide,— brown  (V2O),  gray  (V2O2),  black  (V2O3),  blue  (V2O4), 
and  red  (V2O5).  Upon  the  application  of  heat  vanadium 
unites  with  chlorine,  forming  the  chloride  VC14;  at  a  red 
heat  it  combines  with  nitrogen,  giving  the  nitride  VN.  It 
is  insoluble  in  hydrochloric  and  dilute  sulphuric  acids, 
and  soluble  in  nitric,  hydrofluoric,  and  concentrated  sul- 
phuric acids.  It  is  not  attacked  by  alkaline  solutions,  but 
with  melted  alkalies  forms  the  alkali  vanadates,  with  the 
evolution  of  hydrogen.  The  specific  gravity  of  vanadium 

is  5-5- 

Compounds.  A.  Typical  forms.  The  following  may 
be  considered  typical  compounds  of  vanadium: 

Oxides V20  V2O2      V2O3  V2O4  V2O5 

Chlorides VC12       VC13  VC14 

Oxychlorides ....  VOC1  VOC12 

Bromide VBr3 

Oxybromides VOBr2  VOBr3 

Fluorides V2Fe+  6H2O  VF5 

Double  fluorides. .  V2F6  with  KF,  CoF2,  NiF2,  etc. 

Sulphides VaS,       V2S3  V^O;, 

V2S5 
Sulpho  salts Na3VS3O 

(NH4)3VS4,  etc. 

Sulphate V202(S04)2 

Nitrides VN  VN2 

Vanadates,  ortho,  R3VO4 

Pyo,  R4V207 

meta,  RVO3 

complex,    V2O5  with  P2O5,  MoO3,  WO3,  SiO2>  AsO5,  etc. 
B.    Characteristics.      The     vanadium    compounds     are 
known  in  five  conditions  of  oxidation,  represented  by  the 
five  oxides.     Of  these  conditions  the  highest  is  the  most 


VAKADIUM.  87 

stable  and  is  known  in  the  largest  number  of  salts,  the 
vanadates.  Vanadic  pentoxide  is  reddish  yellow  in  color, 
and,  like  phosphoric  pentoxide,  it  dissolves  readily  in  the 

alkali  hydroxides  and  carbonates.     The  alkali  vanadates 

i 
thus  formed  are  of  the  ortho,  pyro,  and  meta  types,  (RgVO4 ; 

RV2O7;  RVO3).  The  vanadates  are  generally  pale  yellow 
in  color.  They  are  soluble  in  the  stronger  acids  and  with 
the  exception  of  the  alkali  vanadates  insoluble  in  water. 
Vanadic  acid  is  easily  reduced  by  reducing  agents  to  the 
tetroxide  condition,  when  the  solution  becomes  blue.  More 
powerful  reducing  agents  carry  the  reduction  further,  to 
the  trioxide,  or  even  the  dioxide  condition,  but  only  long- 
continued  heating  in  a  current  of  hydrogen  brings  about 
the  reduction  to  the  monoxide  and  the  element. 

Hydrogen  sulphide,  acting  upon  vanadic  acid,  reduces 
it  to  the  tetroxide  condition  or  even  below,  with  a  sepa- 
ration of  sulphur.  Ammonium  sulphide  gives  the  dark- 
brown  solution  of  a  sulpho  salt,  ((NH4)3S3VO?),  and  this 
solution,  when  acidified,  gives  a  brown  oxysulphide  (V2S3O2). 
Vanadium  resembles  arsenic,  phosphorus,  and  nitrogen, 
both  in  the  chemical  structure  of  its  compounds  and  in 
their  behavior  toward  reagents. 

Estimation.*  A.  Gravimetric.  Vanadium  is  usually 
weighed  as  the  pentoxide,  (V2O5),  obtained  (i)  by  precipi- 
tation of  lead  or  barium  vanadate,  treatment  with  sulphuric 
acid,  filtration,  evaporation  of  the  filtrate,  and  ignition;  (2) 
by  precipitation  of  mercury  vanadate  and  ignition,  the 
pentoxide  being  left;  or  (3)  by  precipitation  of  the  ammo- 
nium salt  by  ammonium  chloride  and  ignition  (Berzelius, 
Pogg.  Annal.  xxn,  54;  Gibbs,  Amer.  Chem.  Jour,  v,  371; 
Gooch  and  Gilbert,  Amer.  Jour.  Sci.  [4]  xiv,  205). 


*  See  Die  analytische  Chemie  des  Vanadins,  V.  von  Klecki,  pub.  by  Leo- 
pold Voss,   Hamburg,    1894. 


88  THE  RARER  ELEMENTS. 

B.  Volumetric.  Vanadium  may  be  estimated  volu- 
metrically  (i)  by  reduction  from  the  condition  of  the  pent- 
oxide  to  that  of  the  tetroxide  by  sulphur  dioxide,  and  re- 
oxidation  by  permanganate  (Hillebrand,  Jour.  Amer.  Chem. 
Soc.  xx,  461);  (2)  by  effecting  the  reduction  by  boiling 
with  hydrochloric  acid  or  with  potassium  bromide  or  iodide 
in  acid  solution,  according  to  the  typical  equation  V2O5  + 
2HCl  =  V2O4-f  H2O  +  C12.  The  chlorine,  bromine,  or  iodine 
may  be  distilled,  and  determined  by  suitable  means  in  the 
distillate  (Holverscheit,  Dissertation,  Berlin,  1890;  Fried- 
heim,  Ber.  Dtsch.  chem.  Ges.  xxvm,  2067;  Gibbs,  Proc. 
Amer.  Acad.  x,  250;  Gooch  and  Stookey,  Amer.  Jour.  Sci. 
[4]  xiv,  369;  Curtis,  Amer.  Jour.  Sci.  [4]  xvi),  or  the 
residue  after  boiling  may  be  rendered  alkaline  by  potas- 
sium bicarbonate,  and  reoxidation  effected  by  standard 
iodine  solution  (Browning,  Amer.  Jour.  Sci.  [4]  n,  185); 
(3)  or  the  reduction  may  be  accomplished  by  boiling  with 
tartaric,  oxalic,  or  citric  acid,  and  reoxidation  effected  as 
outlined  above  (Browning,  Zeitsch.  anorg.  Chem.  vn,  158, 
and  Amer.  Jour.  Sci.  [4]  n,  355). 

Separation.  Vanadium  may  be  separated  from  the 
majority  of  the  metallic  bases  (i)  by  fusion  of  material 
containing  it  with  sodium  carbonate  and  potassium  nitrate 
and  extraction  with  water,  vanadium  dissolving  as  sodium 
vanadate;  or  (2)  by  treatment  of  a  solution  containing 
a  vanadate  with  ammonium  sulphide  in  excess,  vanadium 
remaining  in  solution  as  a  sulpho  salt. 

From  arsenic  vanadium  may  be  separated  (i)  by  treat- 
ment with  hydrogen  sulphide,  after  reduction  by  means 
of  sulphur  dioxide,  the  arsenic  being  precipitated  as  the 
sulphide  As2S3;  (2)  by  heating  the  sulphides  of  vanadium 
and  arsenic  in  a  current  of  hydrochloric -acid  gas  at  150°  C., 
the  arsenic  forming  a  volatile  compound  (Field  and  Smith, 
Jour.  Amer.  Chem.  Soc.  xviu,  1051). 

From  phosphorus  vanadium  may  be  separated  by  re- 


EXPERIMENTAL   WORK  ON  YANAD1UM.  89 

duction  of  vanadic  acid  by  means  of  sulphur  dioxide,  and 
precipitation  of  the  phosphorus  as  phosphomolybdate. 

From  molybdenum  the  separation  may  be  accomplished 
by  the  action  of  hydrogen  sulphide  upon  a  solution  of  vana- 
dic and  molybdic  acids  under  pressure, — molybdenum  sul- 
phide being  precipitated, — or  by  the  action  of  ammonium 
chloride  in  excess  upon  a  solution  containing  an  alkali 
vanadate  and  molybdate, — ammonium  metavanadate  being 
precipitated  (Gibbs,  Amer.  Chem.  Jour,  v,  371). 

From  tungsten  vanadium  may  be  separated  by  the 
ammonium  chloride  method  (vid.  Separation  from  molyb- 
denum, above)  (Gibbs,  Amer.  Chem.  Jour,  v,  379). 


EXPERIMENTAL  WORK  ON  VANADIUM. 

Experiment  82.  Extraction  of  vanadic  pentoxide  from 
vanadinite,  ((PbCl)Pb4(V04)3).  Treat  a  few  grams  of  the 
finely  powdered  mineral  with  nitric  acid,  heat  until  nothing 
further  dissolves,  dilate  and  filter.  Remove  the  lead  from 
the  filtrate  by  hydrogen  sulphide,  filter  again,  and  evaporate 
the  filtrate  to  dryness,  adding  a  little  nitric  acid  after  the 
hydrogen  sulphide  has  boiled  out,  to  insure  the  oxidation  of 
the  vanadium.  Ignite  the  residue. 

Experiment    83.     Formation   of   insoluble   vanadate s   of 

ii  ii 

lead,  silver,  and  barium,  (R3(VO4)2,  ortho;  or  R(VO3)2,  meta). 

(a)  To  a  solution  of  an  alkali  vanadate  (ortho  or  meta) 
add  a  solution  of  lead  acetate. 

(b)  Repeat  the  experiment,  substituting  silver  nitrate 
for  lead  acetate.     Note  the  flocky  character  of   the   pre- 
cipitate when  shaken. 

(c)  Use  barium  chloride  as  the  precipitant. 

(d)  Try  the  action  of  nitric  and  acetic  acids  upon  these 
salts. 


9°  THE  RARER  ELEMENTS. 

Experiment  84.  Formation  of  vanadium  pentoxide,  (V205) , 
from  ammonium  vanadate.  Evaporate  a  solution  of  am- 
monium vanadate  to  dryness  and  ignite.  Note  the  crystals 
of  the  pentoxide. 

Experiment  85.  Precipitation  of  vanadium  oxy sulphide, 
(V2S3O2).  (a)  To  a  solution  of  an  alkali  vanadate  add 
ammonium  sulphide.  Note  the  darkening  in  color 
((NH4)3S3VO?).  Acidify  the  solution  with  hydrochloric 
acid.  Note  the  precipitation  of  the  oxysulphide. 

(b)  Note  that  hydrogen  sulphide  in  an  acid  solution 
precipitates  sulphur  and  leaves  a  blue  solution  (V2O4). 

Experiment  86.  Reduction  of  vanadic  acid,  (V205). 
(a)  To  a  solution  of  an  alkali  vanadate  add  a  crystal  of 
tartaric  acid  and  boil.  Note  the  yellow-red  color  of  the 
vanadic  acid  when  the  tartaric  acid  is  first  added,  and 
the  change  to  blue  (V2O4)  produced  on  boiling. 

(b)  Neutralize  the  blue  solution  obtained  in  (a)  with 
sodium  or  potassium  bicarbonate,  and  add  a  solution  of 
iodine  in  potassium  iodide  until,  after  the  liquid  has  stood 
for  a  few  moments,  the  color  of  the  iodine  remains.     Bleach 
the  excess  of  iodine  with  an  alkaline  solution  of  arsenious 
oxide.     Note  that  the  blue  color  has  disappeared  and  the 
vanadium  is  in  the  condition  of  the  pentoxide  (V2O5). 

(c)  Try  the  action  of  other  reducing  agents  upon  vanadic 
acid,  e.g.  oxalic  acid,  hydrochloric  acid,  stannous  chloride, 
zinc  and  hydrochloric  acid,  etc.     Note  that  the  zinc  and 
hydrochloric  acid  carry  the  reduction  below  the  tetroxide 
condition   (V2O4). 

Experiment  87.  Delicate  tests  for  vanadium,  (a)  Acidify 
a  solution  of  an  alkali  vanadate  and  add  hydrogen  dioxide. 
Note  the  red  color  (Maillard). 

(b)  Bring  a  few  drops  of  the  vanadium  solution  into 
contact  with  a  drop  of  strong  sulphuric  acid  to  which  a 
crystal  of  strychnine  sulphate  has  been  added  Note 
the  color,  changing  from  violet  to  rose. 


MOLYBDENUM.  91 

Experiment  88.  Borax-bead  tests  for  vanadium.  Fuse 
a  little  ammonium  vanadate  into  a  borax  bead  and  test 
the  action  of  the  reducing  and  oxidizing  flames  upon  it. 


MOLYBDENUM,  Mo,  96. 

Discovery.  The  name  Molybdena,  derived  from 
lead,  was  originally  applied  to  a  variety  of  substances  con- 
taining lead.  Later  the  term  was  used  to  designate  only 
graphite  and  a  mineral  sulphide  of  molybdenum  which  is 
very  similar  in  appearance  to  graphite,  and  which  was 
confused  with  it.  In  1778  Scheele,  in  his  treatise  on  molyb- 
dena  (Kong.  Vet.  Acad.  Handl.  (1778),  247),  showed  that 
it  differs  from  plumbago,  or  graphite,  in  that  on  being 
heated  with  nitric  acid  it  yields  a  peculiar  white  earth, 
which  he  proved  to  be  an  acid-forming  oxide.  This  he  called 
"acidum  molybdenae, "  and  he  supposed  the  mineral  to  be 
a  compound  of  this  oxide  with  sulphur.  In  1790  Hjelm 
(ibid.  (1790),  50;  Ann.  de  Chim.  iv,  17)  isolated  the  ele- 
ment. 

Occurrence.  Molybdenum  occurs  in  combination  in 
minerals  which  are  somewhat  widely  diffused,  though 
found  in  small  amounts: 

Contains 
Mo 

Molybdite,  MoO3 66-67% 

Molybdenite,  MoS2 60% 

Powellite,  Ca(Mo,W)O4 58-59%* 

Wulfenite,  PbMoO4 37-40%* 

Belonesite,  MgMoO4? 78-79%* 

Scheelite,  CaWO4 traces-  8%* 

Extraction.  Molybdenum  salts  are  usually  obtained 
from  molybdenite,  the  most  abundant  ore,  though  some- 

*MoO8. 


92  THE  RARER  ELEMENTS. 

times  from  other  minerals.     The  following  processes  will 
illustrate  the  methods  employed. 

(1)  From   molybdenite.     The   mineral  is   roasted   until 
sulphur  dioxide  is  no  longer  given  off  and  the  residue  is 
yellow  when  hot  and  white  when  cold.     This  residue  is 
dissolved  in  dilute  ammonium  hydroxide,  and  the  solution 
is    evaporated    to    crystallization.     Heat    drives    off    the 
ammonia    from    the  crystals  and  leaves  the  trioxide  of 
molybdenum. 

(2)  From   molybdenite.     The    mineral   is   treated   with 
nitric  acid  (vid.  Experiment  89). 

(3)  From  wulfenite.     The  mineral  is  fused  with  potas- 
sium polysulphide.     Upon  extraction  with  water  the  lead 
remains  insoluble,  as  the  sulphide,  and  the  molybdenum 
goes  into  solution  as  the  sulpho  salt.     The  filtrate  is  acidi- 
fied with  sulphuric  acid,  and  the  sulphide  of  molybdenum 
is  precipitated   (Wittstein). 

The  Element.  A.  Preparation.  Elementary  molybde- 
num may  be  prepared  (i)  by  passing  dry  hydrogen  over 
either  the  trioxide  or  the  ammonium  salt  at  red  heat, 
and  (2)  by  reducing  the  chlorides  with  hydrogen. 

B.  Properties.  Molybdenum  is  a  gray  metallic  powder, 
which  is  unchanged  in  the  air  at  ordinary  temperatures,  but 
which,  when  heated,  passes  gradually  into  the  trioxide. 
It  is  insoluble "  in  hydrochloric,  hydrofluoric,  and  dilute 
sulphuric  acids,  but  soluble  in  nitric  and  concentrated 
sulphuric  acids,  in  aqua  regia,  in  chlorine  water,  and  in 
melted  potassium  hydroxide,  and  potassium  nitrate.  Its 
specific  gravity  is  8.6. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  molybdenum: 

Oxides MoO        Mo2O3    MoO2     Mo8Ou  Mo3O8  MoO3 

Chlorides Mod,     MoCl3    MoCl4  MoCIa 

Oxychlorides.  MoOC^ 

Mo03da 
Bromides.... MoBra     MoBr9    MoBr4 


MOLYBDENUM  93 

Oxybromide..  MoOaBra 

Oxyiodide....  MoO2I 

Oxyfluorides  .  MoOF^  •  2KF 

+  H.O 

MoO2F2-KF 

+  H20 
Sulphides ....  MoS2  MoS3 ;  MoS4 

Sulphosalt...  R2MoS4 

i 
Molybdates,  many  salts  of  the  type  R2MoO4,  as  K2MoO4;  CaMoO4;  ZnMoO4; 

Ag2MoO4;  etc. 

Molybdenum  trioxide  combines  with  phosphoric  pent- 
oxide  in  the  following  proportions:  P2O5 :  MoO3 : : i :  24, 
1:22,  1:20,  1:18,  1:16,  1:15,  1:5,  as  2K2HPO4-24MoO3  + 
3H2O;  2(NH4)3PO4-i6MoO3  +  i4H2O;  etc.  It  combines 
with  arsenic  pentoxide  as  follows :  As2O5 :  MoO3 : :  i :  20, 
1:18,  1:16,  1:6,  1:2,  as  As2O5«2oMoO3-f  27H2O; 
ioNH3-As2O5-i6MoO3  +  i4H2O;  etc. 

B.  Characteristics.  The  molybdenum  compounds  are 
known  in  various  conditions  of  oxidation  (vid.  Typical 
Forms),  of  which  the  highest,  (MoO3),  is  the  most  stable  and 
comprises  the  largest  number  of  salts.  The  trioxide  is 
white  to  pale  yellow,  and  dissolves  in  potassium,  sodium, 
and  ammonium  hydroxides,  forming  the  molybdates. 
When  strong  reducing  agents,  such  as  zinc  and  hydro- 
chloric acid,  act  upon  acid  solutions  of  molybdates,  the 
reduction  is  said  to  go  as  far  as  the  oxide  Mo5O7,  the  solu- 
tion passing  through  the  colors  of  the  various  oxides, 
violet,  blue,  and  black.  The  oxide  Mo5O7,  however,  is 
very  sensitive  to  oxidation,  for  it  is  changed  in  the  air  to 
the  sesquioxide  (Mo2O3)  as  soon  as  the  reducing  action  has 
ceased.  Acid  solutions  of  the  lower  oxides  give,  on  treatment 
with  the  alkali  hydroxides,  the  corresponding  hydroxides  of 
molybdenum,  Mo2O3  •  3H2O ;  MoO2  -^H2O ;  etc.  The  sulphide 
(MoS3)  is  obtained  by  treating  a  molybdate  with  ammonium 
sulphide  and  acidifying.  Its  color  is  reddish  brown. 

Estimation.     A.  Gravimetric.     Molybdenum  is  generally 


94  THE  RARER  ELEMENTS. 

weighed  as  the  oxide  (MoO3),  obtained  (i)  by  ignition  of 
ammonium  molybdate;  (2)  by  precipitation  of  mercury 
molybdate  and  ignition;  or  (3)  by  precipitation  of  the 
sulphide  and  conversion  into  the  oxide  by  treatment  with 
nitric  acid. 

B.  Volumetric.  Soluble  molybdates  may  be  reduced 
in  acid  solut'on  by  boiling  with  potassium  iodide,  and 
the  iodine  thus  liberated  may  be  passed  into  potassium 
iodide  and  estimated  by  standard  thiosulphate,  the  amount 
of  molybdenum  present  being  calculated  from  the  equation 
2MoO3+2HI=Mo2O5  +  I2+H3O;  or,  after  the  iodine  has 
been  removed  by  boiling,  the  residual  solution  may  be 
rendered  alkaline  by  potassium  bicarbonate  and  reoxidized 
by  standard  iodine  solution  or  potassium  permanganate 
(Mauro  and  Danesi,  Zeitsch.  anal.  Chem.  xx,  507 ;  Fried- 
heim  and  Euler,  Ber.  Dtsch.  chem.  Ges.  xxvm,  2066; 
Gooch  and  Fairbanks,  Amer.  Jour.  Sci.  [4]  n,  156;  Gooch 
and  Pulman,  Amer.  Jour.  Sci.  [4]  xn,  449). 

Separation.  The  general  methods  for  the  separation 
of  molybdenum  from  the  metals  and  alkali  earths  are  the 
same  as  those  described  under  Vanadium. 

From  arsenic  and  phosphorus,  when  present  as  arsenic 
and  phosphoric  acids,  molybdenum  may  be  separated  by 
magnesium  chloride  mixture  in  ammoniacal  solution, 
ammonium-magnesium  arseniate  and  phosphate  being 
precipitated  (Gibbs,  Amer.  Chem.  Jour,  vn,  31.7;  Gooch, 
Amer.  Chem.  Jour,  i,  412). 

For  the  separation  from  vanadium,  vid.  Vanadium. 

From  tungsten  molybdenum  may  be  separated  (i)  by 
the  action  of  warm  sulphuric  acid  of  specific  gravity  1.37 
upon  the  oxides  (MoO3  and  WO3),  molybdic  acid  dissolv- 
ing (Ruegenberg  and  Smith,  Jour.  Amer.  Chem.  Soc. 
xxii,  772) ;  (2)  by  heating  the  oxides  with  hydrochloric- 
acid  gas  at  25o°-27o°  C.,  the  molybdenum  compound 
(MoO3-2HCl)  being  volatilized  (Pechard,  Compt.  rend. 


EXPERIMENTAL    WORK  ON  MOLYBDENUM.  9$ 

cxiv,  173;  Debray,  ibid.  XLVI,  noi);  (3)  by  precipitation 
of  the,  sulphide  of  molybdenum  by  means  of  hydrogen 
sulphide  in  the  presence  of  tartaric  acid  (Rose,  Handbuch 
der  anal.  Chemie  (sechste  Auflage,  1871),  358). 

EXPERIMENTAL  WORK   ON   MOLYBDENUM. 

Experiment  89.  Extraction  of  molybdenum  salts  from 
molybdenite,  (MoS2).  Heat  5  grm.  of  the  finely  powdered 
mineral  with  nitric  acid  until  the  dark  color  has  disap- 
peared. Evaporate  to  dryness,  wash  the  residue  in  warm 
d'lute  nitric  acid,  then  in  water,  and  dissolve  it  in  am- 
monium hydroxide.  Filter,  and  evaporate  the  filtrate  to 
a  small  volume.  Ammonium  molybdate  crystallizes  out, 
which  may  be  converted  into  the  trioxide  by  careful 
ignition. 

Experiment  90.  Precipitation  of  the  sulphides  of  molyb- 
denum, (MoS2;  MoS3).  (a)  Through  a  solution  of  am- 
monium molybdate  acidified  with  hydrochloric  acid  pass 
hydrogen  sulphide.  Note  the  gradual  change  of  color 
of  the  solution,  from  red-brown  to  blue,  and  the  partial 
precipitation  of  the  sulphide  MoS2. 

(6)  To  a  solution  of  ammonium  molybdate  add  am- 
monium sulphide,  or  pass  hydrogen  sulphide  through  an 
alkaline  solution  of  a  molybdate.  Note  the  yellow-brown 
color  ((NH4)2MoS4,  typical).  Acidify  the  solution  and 
note  the  brown  precipitate  (MoS3). 

Experiment  91.  Precipitation  of  ammonium  phospho- 
molybdate  (3(NH4)2O.P2O5.24(MoO3)  -f  2H2O).  To  a  solu- 
tion of  ammonium  molybdate  acidified  with  nitric  acid 
add  a  drop  of  a  solution  of  sodium  phosphate,  and  warm 
gently.  Note  the  yellow  precipitate. 

Experiment  92.  Precipitation  of  the  molybdates  of 
silver,  lead,  and  barium,  (Ag2MoO4,  PbMoO4,  and  BaMoO4, 
typical).  To  separate  solutions  of  ammonium  molybdate, 


9<*  THE  RARER  ELEMENTS. 

neutral  or  faintly  acid  with  acetic  acid,  add  solutions  of 
silver  nitrate,  lead  acetate,  and  barium  chloride  respec- 
tively. Note  the  solvent  action  of  nitric  acid  upon  the 
precipitates. 

Experiment  93.  Reduction  of  molybdic  acid,  (MoO3). 
(a)  Put  a  piece  of  metallic  zinc  into  a  solution  of  ammo- 
nium molybdate  and  add  hydrochloric  acid  until  the  action 
starts.  Note  the  change  in  color  of  the  solution  as  the 
reduction  proceeds  (reddish  yellow,  violet,  bluish,  black). 
To  a  few  drops  of  the  solution  after  reduction  add  potas- 
sium or  sodium  hydroxide.  Note  the  dark-brown  pre- 
cipitate of  the  lower  hydroxides  of  molybdenum  (Mo2(OH)6, 
etc.)  mixed  with  the  hydroxide  of  zinc. 

(b)  Try  the  reducing  action  of  stannous  chloride  upon 
a  molybdate  in  solution. 

(c)  To  a  dilute  solution  of  a  molybdate  which  has  been 
treated  with  zinc  and  hydrochloric  acid,  add  some  potas- 
sium sulphocyanide  in  solution.     Note  the  red  color.    Try 
the  effect  of  adding  ether  and  shaking. 

Experiment  94.  Preparation  of  elementary  molybde- 
num from  ammonium  molybdate.  Heat  a  few  grams  of 
finely  powdered  ammonium  molybdate  until  no  further 
test  for  ammonia  is  obtained  when  a  piece  of  moistened 
red  litmus  paper  is  held  over  the  substance.  Remove  the 
molybdic  trioxide  thus  obtained  to  a  Rose  crucible  and 
heat  for  some  time  in  a  current  of  hydrogen.  Note  the 
gray  powder. 

TUNGSTEN,  W,  184. 

Discovery.  The  minerals  scheelite,  formerly  called 
tungsten  (i.e.  "heavy  stone"),  and  wolframite  have  long 
been  known,  but  until  about  the  middle  of  the  eighteenth 
century  they  were  regarded  as  tin  ores.  In  1781  Scheele 
(Kong.  Vet.  Acad.  Handl.  (1781),  89)  demonstrated  that 
scheelite  contained  a  peculiar  acid  which  he  named  Tung- 


TUNGSTEN.  97 

stic  acid.     Two  years  later  the  brothers  D'Elhujar  showed 
the  presence  of  the  same  acid  in  wolframite. 

Occurrence.  Tungsten  is  found  combined  in  minerals 
which  are  often  associated  with  tin  ores: 

Contains 
W03. 

Wolframite,  (Fe,Mn)WO4. 74~?8% 

Scheelite,  CaWO4 71-80% 

Hubnerite,  MnWO4 73~77% 

Cuprotungstite,  CuWO4. 56-57% 

Cuproscheelite,  (Ca,Cu)WO4 76-80% 

Powellite,  Ca(Mo,W)O4 10-11  % 

Stolzite,  PbWO4 51  circa 

Raspite,  PbWO4 49 

Reinite,  FeWO4 75-76% 

Tungstite,  WO3 100  circa 

Extraction.  Tungstic  acid  is  usually  extracted  from 
wolframite.  Either  of  the  processes  here  indicated  may 
be  followed : 

(1)  5  parts  of  the  mineral  are  fused  with  8.5  parts  of 
dry  sodium  carbonate  and   1.5   parts  of  sodium  nitrate. 
On  treatment  of  the  fused  mass  with  water,  sodium  tung- 
state  is  dissolved,  and  after  filtration  tungstic  acid  is  pre- 
cipitated by  hydrochloric  acid. 

(2)  The  mineral  is  decomposed  by  hydrochloric  acid 
(vid.  Experiment  95). 

The  Element.  A.  Preparation.  Elementary  tungsten 
may  be  obtained  (i)  by  heating  the  acid  in  the  presence 
of  hydrogen;  (2)  by  heating  the  chloride  (WC16)  in  the 
presence  of  hydrogen;  (3)  by  heating  the  acid  with  carbon; 
(4)  by  heating  the  nitride. 

B.  Properties.  Tungsten  is  a  very  hard  powder  rang- 
ing in  color  from  gray  to  brownish  black,  resembling  some- 
times tin,  sometimes  iron.  Although  unchanged  in  the  air 


98  THE  RARER  ELEMENTS. 

at  ordinary  temperatures,  when  heated  in  finely  divided 
condition  it  ignites  and  burns  to  the  oxide  (WO3).  It 
dissolves  when  heated  with  sulphuric,  hydrochloric,  and 
nitric  acids.  It  is  attacked  by  dry  chlorine  at  high  temper- 
atures; also  by  concentrated  boiling  potassium  hydroxide, 
with  the  formation  of  potassium  tungstate.  The  specific 
gravity  of  tungsten  is  from  16.5  to  19.1. 

Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  tungsten  may  be  considered  typical: 

J 

Oxides* WO3\  WO* 

Chlorides WC1,    WC14      WC15  WClfl 

Oxychlorides WOC14 

WO2C12 

Bromides WBr2  WBr5 

Oxybromides WOBr4 

W02Br2 

Iodide WI3 

Double  fluorides  . .  KF  •  WO2F+  H2O      ZnF2  •  WO2F2+  ioH2O  ; 

etc. 

Sulphides WS2  WS3 

Sulpho  salts R2WS4 

R2WS202 
R2WSO3 

Tungstates,  many  salts  of  the  types,  R2WO4  (normal) 

R2W4O13  (meta) 
ReW7024  (para) 

Tungstic  trioxide  (acid)  combines  with  phosphoric 
pentoxide,  arsenic  pentoxide,  and  silicon  dioxide  in  the 
following  proportions: 

P2O5:  WO3:  :  i :  22,  i  :  21,  i  :  20,  i :  16,  1:12,  1:7. 
As2O5  :WO3::  i :  16,  i :  6,  i :  3. 
SiO2:  WO3:  :  i:  12,  i:  10. 

B.    Characteristics.      The    compounds    of    tungsten    are 
very   similar  to   those   of   molybdenum,    and   are   known 

*  Some  authorities  give  three  oxides  between  the  dioxide  and  the  trioxide, 
viz.,  W2O5,  W3O8,  and  W4OU. 


TUNGSTEN.  99 

in  several  conditions  of  oxidation  (vid.  Typical  Forms),  of 
which  the  highest  is  the  most  stable.  The  trioxide,  (WO3), 
united  with  the  bases,  forms  the  largest  number  of  salts, 
the  tungstates.  When  acted  upon  by  reducing  agents, 
tungstic  acid  or  trioxide  may  be  reduced  to  the  dioxide, 
(WO2),  the  solution  becoming  blue,  then  brown.  When 
the  solution  of  a  tungstate  is  acidified,  tungstic  acid  is 
precipitated.  Tungstic  sulphide,  (WS3),  is  obtained  under 
the  same  conditions  as  molybdenum  sulphide,  and  is  brown. 
It  dissolves  in  ammonium  sulphide,  forming  a  sulpho  salt. 

Estimation.  Tungsten  is  ordinarily  weighed  as  the  oxide 
(WO 3),  obtained  (i)  by  igniting  ammonium  tungstate;  (2) 
by  decomposing  the  alkali  tungstates  with  nitric  acid, 
evaporating  to  dryness,  and  extracting  with  water, — tung- 
stic acid  remaining  undissolved;  (3)  by  precipitating  mer- 
cury tungstate  and  driving  off  the  mercury  by  means  of 
heat,  leaving  the  acid  or  oxide ;  (4)  by  boiling  fused  lead 
tungstate  with  strong  hydrochloric  acid, — tungstic  acid 
being  precipitated  (Brearley,  Chem.  News  LXXIX,  64). 

Separation.  Tungsten  may  be  separated  from  the  me- 
tallic bases  and  many  other  elements  by  the  following 
process :  fusion  with  an  alkali  carbonate,  extraction  of  the 
alkali  tungstate  with  water,  acidification  with  nitric  acid, 
evaporation  to  dryness,  and  extraction  with  water, — tung- 
stic acid  remaining  undissolved. 

For  the  separation  of  tungsten  from  molybdenum  and 
vanadium,  see  those  elements.  From  arsenic  and  phos- 
phorus tungsten  is  separated  by  magnesium  mixture 
(Gooch,  Amer.  Chem.  Jour,  i,  412;  Gibbs,  Amer.  Chem. 
Jour,  vii,  337). 

From  tin  the  separation  may  be  accomplished  (i)  by 
ignition  with  ammonium  chloride,  tin  chloride  being  vola- 
tilized (Rammelsberg) ;  (2)  by  fusion  with  potassium  cyanide, 
the  tin  being  reduced  to  the  metal  and  the  tungsten  being 
converted  into  a  soluble  tungstate  (Talbot). 


loo  THE  RARER  ELEMENTS. 

EXPERIMENTAL  WORK  ON  TUNGSTEN. 

Experiment  95.  Extraction  of  tungstic  acid  from  wol- 
framite ((Fe,Mn)WO4).  Treat  5  grm.  of  the  finely  powdered 
mineral  with  about  10  cm.3  of  a  mixture  of  equal  parts  of 
hydrochloric  acid  and  water,  and  boil  as  long  as  any  action 
seems  to  take  place.  Decant  the  solution,  add  to  the 
residue  about  10  cm.3  of  a  mixture  of  nitric  and  hydro- 
chloric acids  (aqua  regia),  and  warm.  Add  more  acid  if 
necessary,  and  continue  this  treatment  until  the  residue  is 
yellow,  then  filter  and  wash.  Warm  the  yellow  mass  with 
ammonium  hydroxide  as  long  as  any  solvent  action  is 
observed,  and  filter.  Evaporate  the  filtrate  to  dryness 
and  ignite  the  ammonium  tungstate  to  obtain  tungstic 
acid. 

Experiment  96.  Formation  of  sodium  tungstate, 
(Na2WO4,  typical).  Dissolve  a  little  tungstic  acid  in  a 
solution  of  sodium  carbonate. 

Experiment  97.  Precipitation  of  tungstic  sulphide, 
(WS3),  and  formation  of  the  sulpho  salt  ((NH4)2WS4).  (a)  To 
a  solution  of  sodium  or  ammonium  tungstate  add  ammo- 
nium sulphide,  and  acidify  with  hydrochloric  acid. 

(6)  Try  the  action  of  hydrogen  sulphide  upon  a  soluble 
tungstate. 

(c)  Try  the  action  of  ammonium  sulphide  upon  tungstic 
sulphide. 

Experiment  98.  Precipitation  of  tungstic  acid,  (WO3). 
Acidify  a  concentrated  solution  of  a  tungstate  with  hydro- 
chloric or  nitric  acid  and  boil. 

Experiment  99.     Precipitation  of  barium,  lead,  and  silver 

i 
tungstates,   (R2WO4,  typical).      To  separate   portions    of  a 

solution  of  sodium  tungstate  acidified  with  acetic  acid  add 
solutions  of  barium,  lead,  and  silver  salts  respectively. 

Experiment  100.  Reduction  of  tungstic  acid,  (a)  To 
a  solution  of  a  tungstate  (e.g.  sodium  tungstate)  add  a 


URANIUM.  1 01 

solution  of  stannous  chloride.     Acidify  with  hydrochloric 
acid  and  warm  gently. 

Experiment  101.  Salt  of  phosphorus  bead  tests.  Make 
a  bead  of  microcosmic  salt,  and  heat  it  in  the  oxidizing 
and  reducing  flames  with  a  small  particle  of  tungstic  acid. 
Try  the  effect  of  a  small  amount  of  ferrous  sulphate  upon 
the  bead  heated  in  the  reducing  flame. 

URANIUM,  U,  238.5. 

Discovery.  Klaproth,  in  the  year  1789,  discovered  that 
the  mineral  pitch-blende,  supposed  to  be  an  ore  of  zinc, 
iron,  or  tungsten,  contained  a  "half-metallic  substance'* 
differing  in  its  reactions  from  all  three  (Crell  Annal.  (1789) 
ii,  387).  This  he  named  Uranium  in  honor  of  Herschel's 
discovery  of  the  planet  Uranus  in  1781.  The  body  that 
Klaproth  obtained  was  really  an  oxide  of  uranium,  as 
Peligot  showed  in  1842,  when  he  succeeded  in  isolating 
the  metal  (Ann.  de  Chim.  (1842)  v,  5). 

Occurrence.  Uranium  is  found  combined  in  a  few  min- 
erals, most  of  them  rare.  Pitch-blende  is  the  most  abun- 
dant source. 

Uraninite  (pitchblende),  UO3  •  UO2  -  PbO  •  N,  etc.,  contains   75-85%  (UO2+  UOj) 

Gummite,  (Pb,Ca)U3SiO12-6H2O?,  "  61-75%  UO3 

Thorogummite,  UO3-3ThO2-3SiO2-6H2O,  "  22-23%    " 

Mackintoshite,  UO2 •  3ThO2 •  3SiO2 •  3H2O,  "  2 1-22%  UO2 

Uranophane,  CaO •  2UO3  •  28! O2  •  6H2O,  "  53-67%  UO3 

Uranosphaerite,  (BiO)2U2Or  3H2O,  "  50-51%    " 

Walpurgite,  Bi10(UO2)3(OH)24(AsO4)4,  "  20-21%    " 

Carnotite,  K2O  •  2U2O3  •  V2O5  •  3H2O,  "  62-65%  U2O, 

Torbernite,  Cu(UO2)2P2O8-8H2O,  "  57-62%  UO8 

Zeunerite,  Cu(U02)2As208-8H2O,  "  55-56%    " 

Aitfcmtte,Ca(U02),P2(V8HaO,  55-62%    " 

Uranospinite,  Ca(UO2)2As2O8-8H2O,  "  59~6o%    " 

Uranocircite,  Ba(U02)2P2O8-8H2O,  56-57%    " 

Johannite,  sulphate,  formula  doubtful,  67-68%    " 

Uranopilite,  CaO.8UO3.2SO3-25H3O,  "  77~78%    " 

Thorite,  ThSiO4,  "  1-10%    •« 


102 


THE  RARER  ELEMENTS. 


Phosphuranylite,  (UO2)3P2O8-6H2O, 
Trogerite,  (UO2)3As2O8  •  1 2H2O, 

Uranothallite,  2CaCO3 •  U(CO3)2 -xioH2O, 
Liebigite,  CaCO3  •  (UO2)CO3  •  2oH2O, 
Voglite,  complex  carbonate, 

Hatchettolite,  R(Nb,Ta)2Oc.H2O, 

in 
Ferguson! te,  R(Nb,Ta)O4, 

Sipylite,  complex  niobate, 

n  in 
Samarskite,  R3R2(Nb,Ta)8O21, 

o 

Annerpdite,  complex, 
Hielmite,  complex, 

in  in 

Euxenite,  R(NbO3)3  •  R2(TiO3)3  •  |H2O, 

in  in 

Polycrase,  R(NbO3)3.2R(TiO3)3-3H2O, 


contains. 

M 


72-77%  UOS 
63-64%    " 

35-37%  U02 

36-38%  UO, 

37%  U02 

15-16%  U08 

o-  8%  U02 

3-4%    " 

10-13%  U08 

16-17%  UO2 

0-5%    ' 


1-19%    " 


Extraction.  Uranium  salts  may  be  extracted  from  pitch- 
blende as  follows: 

(1)  The  mineral  is  decomposed  with  nitric  acid,   the 
acid  solution  is  evaporated  to  dryness,  and  the  mass  is 
extracted  with  water.     The  residue,  which  consists  largely 
of  lead  sulphate,  iron  arseniate,  and  iron  oxide,  is  filtered 
off,  and  on  evaporation  of  the  solution  impure  nitrate  of 
uranium  crystallizes  out,   which  may  be  purified  by  re- 
crystallization   ( Peligot) . 

(2)  The   mineral  is   decomposed  by  aqua   regia    (vid. 
Experiment  102). 

The  Element.  A.  Preparation.  Metallic  uranium  may 
be  obtained  (i)  by  heating  a  mixture  of  the  chloride  UC1S 
with  sodium  and  potassium  chloride  in  a  porcelain  cru- 
cible surrounded  by  powdered  carbon  contained  in  another 
crucible  (Peligot) ;  (2)  by  heating  a  mixture  of  uranium 
chloride,  sodium  chloride,  and  metallic  sodium  in  a  closed 
iron  crucible. 

B.  Properties.  Uranium  is  a  somewhat  malleable  white 
metal  with  much  the  appearance  of  nickel.  Heated  in 
air  or  oxygen  to  a  temperature  of  1 50°-!  70°  C.  it  burns 


UR/4N1UM.  I03 

to  the  oxide ;  at  ordinary  temperatures  the  oxidation  takes 
place  slowly.  Uranium  dissolves  slowly  in  cold  dilute  sul- 
phuric acid,  and  more  rapidly  upon  the  application  of  heat. 
It  is  soluble  in  nitric  and  hydrochloric  acids.  It  is  attacked 
by  chlorine  at  i5o°C.  and  by  bromine  at  240°  C.  The 
caustic  alkalies  have  no  apparent  action  upon  the  element. 
The  specific  gravity  of  uranium  is  18.6. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  uranium: 

Oxides  * UOa  U3O8(UO2  + 

2UO3)  UO3 

Carbonates UO2CO3  •  2K2CO3 

U02C03-2(NH4)2C03 

Chlorides UC13     UC14       UC15  UO2C12 

Bromides UBr3    UBr4       UBr8  UO2Br2 

lodate U02(I03)2 

Fluorides UF4  UO2F2 

UO2F2-NaF,  etc. 
Sulphides US  UjS,     US2  UOS2 

U02S 

Sulphates U(SO4)2+  UO2SO4+  3|H2O 

4H20 

Nitrate UO2(NO3)2+  6H2O 

Nitride U3N4 

Ferrocyanides UFe(CN)8  (UO2)3K2(FeC8N8), 

Phosphates,  ortho.  UOHPO4  (UO2)5H2(PO4)4 

pyro..  (UO)2P207  (UO2)2P2O7 

meta..  UO(PO3)2  UO2(PO3)2 

Arseniate UO2H  AsO4+  4H2O 

Uranates,  of  types  R2UO4>  R2U2O7,  and  R4UO8. 

B.  Characteristics.  Uranium  differs  from  vanadium, 
molybdenum,  and  tungsten  in  manifesting  less  marked 
acidic  qualities.  The  chief  classes  of  salts  are  the  uranyl, 
in  which  uranium  shows  its  highest  degree  of  oxidation, 
corresponding  to  the  oxide  UO3  (e.g.  UO2C12),  and  the 
uranous,  of  which  the  oxide  UO2  is  the  type  (e.g.  UC14). 
The  uranyl  salts  are  the  more  stable  and  better  known. 
They  may  be  reduced  by  zinc  and  hydrochloric  acid  to 

*  Other  oxides  less  well  known  than  those  given  above  are  of  the  follow- 
ing forms:  UO,  U2O3,  U3O4,  and  UO4. 


104  *      THE  RARER  ELEMENTS. 

the  lower  condition.  The  uranous  salts  are  easily  oxidized 
to  the  higher  form.  The  uranyl  salts  are,  in  general, 
yellow,  the  uranous  greenish.  The  two  conditions  of 
oxidation  may  be  further  distinguished  by  the  following 
reactions:  the  precipitate  resulting  from  the  action  of 
ammonium  sulphide  upon  uranyl  salts  is  reddish  brown, — 
upon  uranous  salts,  light  green;  the  precipitate  resulting 
from  the  action  of  potassium  ferrocyanide  upon  uranyl 

salts  is  blood-red, — upon  uranous  salts   yellowish   green. 

i  i 

Uranates  of  the  types  R2UO4  and  R2U2O7  are  formed  by 

the  combination  of  the  oxide  UO3  with  the  strong  bases. 

Estimation.*  A.  Gravimetric.  Uranium  may  be 
weighed  (i)  as  urano-uranic  oxide  (U3O8),  obtained  by 
precipitation  of  ammonium  uranate  by  means  of  ammonia, 
and  ignition  in  air  or  oxygen;  (2)  as  urano-uranic  oxide, 
precipitated  electrolytically  by  a  current  of  0.18  ampere 
and  3  volts  at  a  temperature  of  70°  C.  (Smith  and  Wallace, 
Jour.  Amer.  Chem.  Soc.  xx,  279;  Smith  and  Kollock,  ibid, 
xxm,  607);  (3)  as  uranous  oxide  (UO2),  obtained  by  ig- 
nition of  urano-uranic  oxide  in  a  current  of  hydrogen; 
(4)  as  the  pyrophosphate  ((UO2)2P2O7),  obtained  by  pre- 
cipitation by  means  of  ammonium  phosphate  in  the  pres- 
ence of  ammonium  acetate,  and  ignition. 

B.  Volumetric.  Uranium  may  be  estimated  volumet- 
rically  by  reduction  from  the  higher  (UO3)  to  the  lower 
,(UO2)  condition  of  oxidation  by  means  of  zinc  and  sul- 
phuric acid,  and  oxidation  with  permanganate,  according 
to  the  following  formulae  (Pulman,  Amer.  Jour.  Sci.  [4]  xvi) : 

(1)  U02S04  +  Zn  +  2H2S04=  ZnSO4  +  U(SO4) 

(2)  2KMn04  +  5U(S04)2  +  2H20= 

2KHSO4  +  2MnSO4  +  H2SO4 

Separation.*      From   the  metals  which  precipitate  sul- 
phides with  hydrogen  sulphide  in  acid  solution,  uranium 
*  Vid.  Kern,  Jour.  Amer.  Chem.  Soc,  XXHI,  685. 


EXPERIMENTAL   WORK  ON  URANIUM.  105 

may  be  separated  by  hydrogen  sulphide.  From  iron, 
nickel,  and  other  members  of  its  own  group  it  may  be 
separated  by  ammonium  sulphide  in  the  presence  of  an 
excess  of  sodium  or  ammonium  carbonate,  the  uranium 
salt  remaining  in  solution.  From  the  alkalies  and  alkali 
earths  the  separation  may  be  accomplished  by  means  of 
ammonium  sulphide  in  the  presence  of  ammonium  chloride, 
uranium  oxysulphide  being  precipitated. 


EXPERIMENTAL  WORK  ON  URANIUM. 

Experiment  102.  Extraction  of  uranium  salts  from  pitch" 
blende.  Warm  5  grm.  of  pulverized  pitch-blende  with 
aqua  regia  until  the  decomposition  is  complete,  and  remove 
the  excess  of  acid  by  evaporation.  Extract  with  water  and 
boil  the  solution  a  few  minutes  with  sulphurous  acid  to 
reduce  the  arsenic  acid.  When  the  liquid  is  at  about  60°  C., 
pass  hydrogen  sulphide  through  to  the  complete  precipita- 
tion of  arsenic,  copper,  lead,  bismuth,  and  tin.  Filter, 
oxidize  the  filtrate  with  nitric  acid,  and  precipitate  with 
ammonium  hydroxide.  Treat  the  precipitate  with  hot 
concentrated  ammonium  carbonate,  filter,  and  allow  the 
filtrate  to  cool.  The  double  carbonate  of  uranium  and 
ammonium  will  separate.  A  further  precipitate,  of  crude 
ammonium  uranate,  may  be  obtained  by  boiling  the  mother- 
liquor. 

Experiment   103.     Precipitation   of   sodium,   potassium, 

i 
or  ammonium  uranate,  (RJJfi?,   typical).     To  a  solution 

of  a  uranyl  salt  add  sodium,  potassium,  or  ammonium 
hydroxide.  Note  the  yellow  color  of  the  precipitate  and 
the  insolubility  in  excess  of  the  reagent.  Repeat  the 
experiment  with  tartaric  acid  present  in  the  solution. 

Experiment  104.  Formation  of  the  soluble  double  car- 
bonates of  uranium  with  sodium  or  potassium,  and  uranium 


lo6  THE  RARER  ELEMENTS. 


with  ammonium,  (UO-jCOg^R/X),,)  •  (a)  To  a  solution  of 
a  uranyl  salt  add  a  solution  of  sodium  or  potassium  car- 
bonate, noting  the  first  and  the  final  effects.  Try  the  re- 
sult of  boiling,  and  of  adding  sodium  or  potassium  hydrox- 
ide to  a  separate  portion  of  the  clear  solution. 

(b)  Try  similarly  the  action  of  ammonium  carbonate 
upon  a  uranyl  salt  in  solution.     Note  the  ready  solvent 
action  of  an  excess  of  the  carbonate,  and  the  precipitation 
of  ammonium  uranate,    ((NH4)2U2O7),  on  boiling. 

(c)  To  a  solution  of  a  uranyl  salt  add  hydrogen  di- 
oxide  and    potassium  or   sodium   carbonate.       Note    the 
cherry-red  color  (Aloy). 

Experiment  105.  Precipitation  of  uranyl  ferrocyanide, 
((U02)3K2(FeC6N6)2  or  (UO2)2FeC6N6).  (a)  To  a  very  dilute 
solution  of  a  uranyl  salt  add  a  little  potassium  ferrocyanide 
in  solution.  Note  the  red  precipitate.  This  is  a  delicate 
test  for  uranyl  salts. 

(b)  Try  similarly  the  action  of  potassium  ferricyanide. 

Experiment  106.  Precipitation  of  uranyl  phosphate, 
(UO2HPO4).  To  a  solution  of  a  uranyl  salt  add  a  solution 
of  hydrogen  disodium  phosphate.  Try  the  action  of  the 
common  acids  upon  the  precipitate. 

Experiment  107.  Precipitation  of  uranyl  sulphide, 
(UO2S).  (a)  To  a  solution  of  a  uranyl  salt  add  ammonium 
sulphide.  Note  the  dark-brown  color  of  the  precipitate, 
and  the  insolubility  in  excess  of  the  reagent. 

(b)  Try  the  action  of  hydrogen  sulphide  upon  a  uranyl 
salt. 

Experiment  108.  Reduction  of  uranyl  salts,  (a)  To  a 
solution  of  a  uranyl  salt  add  zinc  and  sulphuric  acid.  Note 
the  change  of  color  from  yellow  to  green. 

(6)  Bring  about  the  reduction  with  magnesium  and 
acid.  Test  the  uranous  salt  in  solution  with  potassium 
ferrocyanide  and  with  ammonium  sulphide. 


TELLURIUM. 


107 


TELLURIUM,  Te,   127.6. 

Discovery.  Native  tellurium,  which  is  quite  widely 
distributed  in  small  quantities,  was  a  puzzle  to  the  early 
mineralogists.  Because  of  its  non-metallic  properties  and 
its  metallic  luster  it  was  known  as  aurum  paradoocum  and 
metallum  problematicum.  In  1782  Muller  von  Reichen- 
stein,  after  some  careful  work  on  this  interesting  substance, 
suggested  that  a  peculiar  metal  might  be  present.  Acting 
on  the  suggestion,  Klaproth  undertook  an  investigation, 
and  in  1798  he  demonstrated  that  the  "metal"  was  not 
identical  with  any  known  element.  He  proposed  the  name 
Tellurium  from  tellus,  earth  (Crell  Annal.  (1798)  i,  91). 

Occurrence.  Tellurium  occurs  in  combination  and  also, 
sparingly,  native. 

Petzite,  (Ag,Au)2Te,                          contains..  32-35%  Te 

Goldschmidtite,  Au-jAgTe^  "  .  .  59-60%  " 

Hessite,  Ag,Te,  "  ..  37~44%  " 

Altaite,  PbTe,  "  .  .  37-38%  " 

Coloradoite,  HgTe,  "  .  .  38-39%  " 

Melonite,  Ni2Te3,  "  .  .  73-76%  " 

Kalgoorlite,  HgAu.AgeTee,  "  ..  37-56%  " 

Sylvanite,  (Au,Ag)Te2,  "  ..  58-62%  " 

Calaverite,  (Au,Ag)Te2-AuTe2,  "  ..  56-58%  " 

Krennerite,  (Au,Ag)Te2-AuTe2,  "  -.38-59%  " 

Nagyagite,  Au2Pb14Sb3Te7S17,  "  ..  15-31%  " 

Tapalpite,  3Ag2(S,Te) -Bi2(S,Te)3?,       "  ..  20-24%  " 

Tetradymite,  Bi2Te3S3,  "  ..  33-49%  " 

Grunlingite,  Bi4TeS3,  "  ..12-13%  " 

Rickardite,  Cu2Te  •  2CuTe,  "  ..  59-60%  " 

Joseite,  formula  doubtful,  "  ..  15-16%  " 

Wehrlite,     4<             "  "  29-35%  " 

Stiitzite,Ag4Te?,  "  ..  22-23%  " 

Tellurite,  TeO2,  "  ..  79-80%  " 


io8  THE  R4RER  ELEMENTS. 

Montanite,  Bi2(OH)4Te06?,  contains..  24-28%  TeO3 

Emmonsite,  formula  doubtful,  "        ..  59-60%  Te 

Durdenite,  Fe2(Te03)3.4H20,  "       ..  47-64%  TeO2 

Tellurium  (native),  Te,  "       .  .  93-97%  Te 

Selen-tellurium,  3Te2Se,  "       ..  70-71%    " 

Extraction.  Tellurium  may  be  extracted  by  the  fol- 
lowing methods : 

(1)  From  tellurium  bismuth  (tetradymite).     The  mineral 
is  mixed  with  its  own  weight  of  sodium  carbonate,  and 
oil  is  added  until  the  mass  has  the  consistency  of  thick 
paste.      This  is  heated  strongly  in  a  well-closed  crucible 
and  then  extracted  with  water.     The  extract,  containing 
sodium  sulphide  and  sodium  telluride,  (Na2Te),  is  separated 
by  filtration  from  the  insoluble  matter  and  left  exposed 
to  the  air.     The  tellurium  separates  as  a  gray  powder.     It 
may  be  purified  by  distillation   (Berzelius). 

(2)  From  sylvanite  or  nagy agile.     The  mineral  is  treated 
with   hydrochloric    acid,    which   dissolves   the   antimony, 
arsenic,  etc.     The  residue  is  dissolved  in  aqua  regia,  the 
excess  of  acid  is  removed  by  evaporation,  and  the  gold  is 
precipitated  by  ferrous  sulphate.     After  the  removal  of 
the  gold  by  filtration  the  tellurium  is  precipitated  by  sul- 
phur dioxide   (Von  Schrotter). 

(3)  From  flue-dust  containing  tellurium.     The  material 
is  treated  with  strong  commercial  hydrochloric  acid  (vid. 
Experiment  109). 

The  Element.  A.  Preparation.  Elementary  tellurium 
may  be  obtained  (i)  by  the  action  of  reducing  agents,  as 
sulphurous  acid  or  stannous  chloride,  upon  the  salts  of  tel- 
lurium; and  (2)  by  the  action  of  air  upon  soluble  tellurides. 

B.  Properties.  Tellurium  is  generally  considered  a  non- 
metal,  though  Berzelius  classed  it  with  the  metals.  It  is 
known  in  two  conditions:  (i)  the  crystalline,  in  which  the 
element  has  a  luster  like  silver,  and  (2)  the  amorphous.  It 


TELLURIUM. 


109 


is  unchanged  in  the  air  at  ordinary  temperatures,  but  when 
heated  in  air  or  oxygen  it  burns  with  a  green  flame,  forming 
the  dioxide  (TeO2).  It  is  not  attacked  by  hydrochloric 
acid,  but  is  acted  upon  slowly  by  concentrated  sulphuric 
acid,  with  evolution  of  sulphur  dioxide.  It  is  oxidized  by 
nitric  acid  and  aqua  regia  to  tellurous  acid,  (H2TeO3),  and 
is  dissolved  in  hot  caustic  potash,  forming  the  telluride 
and  tellurite  (K2Te;  K2TeO3).  It  combines  with  metals 
to  form  tellurides.  Like  selenium  and  sulphur,  it  is  a  poor 
conductor  of  heat  and  electricity.  Its  specific  gravity  is 
from  6.1  to  6.3. 

Compounds.     A.   Typical  forms.     The  following  are  typ- 
ical compounds  of  tellurium: 


Oxides TeO 

Chlorides TeCl2 

Oxychloride 

Bromides TeBr2 

Oxybromide 

Iodides TeI2 

Fluoride 

Double  fluoride 

Sulphite TeSO, 

Sulphate '..... 

Sulphides  (or  sulpho  salts). 


TeO2 

TeCl4 

TeOCl2 

TeBr4 

TeOBr2 

TeI4 

TeF, 

TeF! 


TeO3 


KF 


2TeO2-SO3 
TeS2.3K2S 
TeS2-Bi2S3,  etc. 


H2TeO4* 


Tellurides H2Te 

As2Te3 

K2Te,  etc. 

Acids  (tellurous  and  telluric)  H2TeO3 

Salts  (tellurites  and  tellurates)  R2TeO3  R2TeO4 

B.  Characteristics.  The  compounds  of  tellurium  closely 
resemble  in  general  structure  those  of  sulphur,  and,  as  will 
appear  later,  those  of  selenium.  Hydrogen  telluride,  (H2Te) , 


*  Gutbier  favors  the  formula  HcTeOn. 


no  THE  RARER  ELEMENTS. 

like  hydrogen  sulphide,  is  a  gaseous  substance,  and  it  pre- 

i 
cipitates  metallic  tellurides,  (R2Te) ,  similar  to  the  sulphides. 

Two  oxides,  tellurous,  (TeO2),  and  telluric,  (TeO3),  are  well 
known,*  but,  unlike  the  corresponding  oxides  of  sulphur, 
they  are  very  sparingly  soluble  in  water.  The  acids, 
(H2TeO3;  H2TeO4),  may  be  formed  by  acidifying  solutions 
of  the  alkali  salts  (e.g.  Na2TeO3  or  Na2TeO2)  which  have 
been  formed  by  the  action  of  the  alkali  hydroxides  upon 
the  oxides  (TeO2;  TeO3).  Many  tellurites  and  tellurates, 
(R2TeO3;  R2Te04),  may  be  formed  by  treating  the  alkali 
tellurites  or  tellurates  with  soluble  salts  of  the  various 
bases.  Two  chlorides  are  known,  (TeCl2;  TeCl4),  both  of 
which  are  decomposed  by  water.  The  corresponding 
bromides  and  iodides  are  also  known.  In  general,  com- 
pounds of  tellurium  are  easily  reduced  to  the  element. 
The  reduction,  however,  is  not  accomplished  quite  so 
readily  as  in  the  case  of  selenium  compounds. 

Estimation. f  A.  Gravimetric.  Tellurium  is  usually 
weighed  as  the  element,  obtained  by  treating  solutions 
of  tellurium  compounds  (i)  with  sulphur  dioxide;  (2) 
with  hydrazine  sulphate  in  ammoniacal  solution  (Jan- 
nasch,  Ber.  Dtsch.  chem.  Ges.  xxxi,  2377);  (3)  with  hydra- 
zine hydrate  or  its  salts  in  acid  or  alkaline  solution  (Gut- 
bier,  Ber.  Dtsch.  chem.  Ges.  xxxiv,  2724);  (4)  with  sul- 
phur dioxide  and  potassium  iodide  (Frericks,  J.  pr.  Chem. 
[2]  LXVI,  261);  (5)  with  hypophosphorus  acid  (Gutbier, 
Zeitsch.  anorg.  Chem.  xxxn,  295) ;  (6)  with  grape-sugar 
in  alkaline  solution  (Stolba,  vid.  Kastner,  Zeitsch.  anal. 
Chem.  xiv,  142) ;  or  (7)  with  acid  sodium  sulphite  or  mag- 
nesium (vid.  Experiment  109). 

It  may  be  weighed  also  as  the  sulphate,  (2TeO2-SO3), 

*  A  monoxide,  (TeO),  also  has  been  described. 

t  See  Gutbier,  Studien  uber  das  Tellur,  pub.  by  Hirschfeld,  Leipzig,  1902; 
Mac  Ivor,  Chem.  News  LXXXVII,  17,  162. 


TELLURIUM.  Hi 

obtained  by  treating  elementary  tellurium  with  a  mixture 
of  nitric  and  sulphuric  acids  and  evaporating  (Metzner, 
Ann.  Chim.  Phys.  [7]  xv,  203). 

B.  Volumetric.  Tellurium  may  be  estimated  volumet- 
rically  (i)  by  the  reduction  of  telluric  acid  to  tellurous  by 
means  of  potassium  bromide  in  sulphuric  acid  solution, 
(H2TeO4  +  2HBr  =  H2TeO3  +  H2O  +  Br2),  the  bromine  being 
passed  into  potassium  iodide,  and  the  iodine  estimated 
by  standard  thiosulphate  (Gooch  and  Rowland,  Amer. 
Jour.  Sci.  [3]  XLVIII,  375);  (2)  by  the  reducing  action  of 
strong  hydrochloric  acid  upon  soluble  tellurates,  chlorine 
being  set  free  and  passed  into  potassium  iodide  with  libera- 
tion of  iodine,  as  above;  (3)  by  the  action  of  standard 
potassium  iodide  solution  upon  a  solution  of  tellurous 
acid  containing  twenty-five  per  cent,  by  volume  of  strong 
sulphuric  acid,  (H2TeO3  +  4H2SO4  +  4KI  =  TeI4  +  4KHSO4  + 
3H2O),  tellurous  iodide  being  precipitated  as  a  black,  curdy 
mass,  which,  when  shaken,  separates  in  such  a  manner  that 
the  point  when  precipitation  ceases  can  easily  be  detected ; 
the  quantity  of  tellurium  present  is  calculable  from  the 
quantity  of  potassium  iodide  used  (Gooch  and  Morgan, 
Amer.  Jour.  Sci.  [4]  n,  271);  (4)  by  the  oxidation  of  tellu- 
rous acid  by  means  of  standard  potassium  permanganate 
in  acid  or  alkaline  solution  (Norris  and  Fay,  Amer.  Chem. 
Jour,  xx,  278;  Gooch  and  Peters,  Amer.  Jour.  Sci.  [4] 
viii,  122). 

Separation.*  From  the  elements  not  easily  reduced 
from  their  compounds  to  elementary  form,  tellurium  may 
be  separated  in  general  by  the  action  of  sulphur  dioxide  in 
faintly  acid  solution ;  this  precipitates  elementary  tellurium. 
From  bismuth  tellurium  is  separated  by  the  action  of 
potassium  sulphide  upon  the  precipitate  thrown  down 
from  solutions  by  hydrogen  sulphide, — the  tellurium  dis- 

*  See  Gutbier,  Studien  iiber  das  Tellur. 


112  THE  RARER  ELEMENTS. 

solving.  From  antimony  the  separation  may  be  accom- 
plished (i)  by  hydrazine  hydrate,  the  tellurium  being  pre- 
cipitated (Gutbier,  Zeitsch.  anorg.  Chem.  xxxn,  260); 
(2)  by  treatment  of  a  solution  of  sulpho-tellurite  and  sul- 
pho-antimonite  with  20%  hydrochloric  acid  in  the  pres- 
ence of  tartaric  acid,  the  tellurium  separating  out  (Muth- 
mann  and  Schroder,  Zeitsch.  anorg.  Chem.  xiv,  433).  From 
silver  tellurium  is  separated  by  hydrochloric  acid,  the 
silver  being  precipitated;  from  gold  by  the  action  of  heat 
on  the  two  metals,  tellurium  being  volatilized;  from  mer- 
cury by  the  action  of  phosphorus  acid  upon  a  cold  dilute 
hydrochloric  acid  solution  of  the  salts,  mercurous  chloride 
being  precipitated. 

From  selenium  tellurium  may  be  separated  (i)  by 
hydroxylamme  in  strong  hydrochloric  acid  solution,  the 
selenium  being  precipitated  (Jannasch  and  Miiller,  Ber. 
Dtsch.  chem.  Ges.  xxxi,  2388) ;  (2)  by  sulphur  dioxide  in 
strong  hydrochloric  acid  solution,  selenium  being  pre- 
cipitated (Keller,  Jour.  Amer.  Chem.  Soc.  xix,  771,  and 
xxn,  241);  (3)  by  fusion  of  the  elements  with  potassium 
cyanide  in  the  presence  of  hydrogen,  tellurium  being  pre- 
cipitated when  air  is  passed  through  a  solution  of  the  melt ; 

(4)  by  the  action  of  ferrous  sulphate  (vid.  Experiment  109) ; 

(5)  by  "the  greater  volatility  of  the  bromide  of  selenium 
(Gooch  and  Peirce,  Amer.  Jour.  Sci.  [4]  i,  181). 

EXPERIMENTAL  WORK  ON  TELLURIUM. 

Experiment  109.  Extraction  of  tellurium  from  flue-dust,  or 
from  waste  products  from  the  electrolytic  refining  of  copper. 
Treat  about  logrm.  of  the  material  with  strong  commercial 
hydrochloric  acid  until  nothing  further  dissolves,  and  filter. 
To  a  small  portion  of  the  filtrate  add  ferrous  sulphate,  and 
warm  gently.  The  presence  of  selenium  will  be  indicated  by 
a  reddish  precipitate.  If  selenium  has  thus  been  shown  to 


EXPERIMENTAL    WORK  ON  TELLURIUM.  1*3 

be  present,  take  about  5  cm.3  of  the  original  filtrate,  precipi- 
tate the  selenium  and  tellurium  by  acid  sodium  sulphite  or  by 
magnesium,  wash  this  precipitate,  return  it  to  the  remainder 
of  the  filtrate,  and  heat  to  boiling.  The  selenium  present 
will  be  precipitated  by  the  tellurium.  Remove  the  selen- 
ium by  filtration  and  set  it  aside  for  later  use  (vid.  Experi- 
ment 119).  From  the  filtrate  precipitate  the  tellurium 
by  acid  sodium  sulphite  or  by  magnesium  (Crane,  Amer. 
Chem.  Jour,  xxxin,  408). 

Experiment  no.  Action  of  strong  sulphuric  acid  upon 
tellurium.  To  a  small  amount  of  elementary  tellurium 
add  a  few  cm.3  of  strong  sulphuric  acid  and  warm.  Note 
the  reddish- violet  color.  This  reaction  constitutes  a  good 
test  for  tellurium. 

Experiment  1 1 1 .  Preparation  of  tellurium  dioxide,  (TeO2) . 
To  a  small  amount  of  elementary  tellurium  add  nitric 
acid,  evaporate  to  dryness,  and  heat  gently. 

Experiment    112.       Formation   of    an    alkali    tellurite, 

i 

(R2TeO3).  Dissolve  a  little  tellurium  dioxide  in  a  solution 
of  sodium  or  potassium  hydroxide. 

Experiment  113.  Formation  of  telluric  acid,  (H2TeO4). 
To  a  solution  of  an  alkali  tellurite  add  sulphuric  acid  until 
the  precipitate  first  formed  dissolves.  Then  add  gradually 
a  solution  of  potassium  permanganate  until  no  further 
bleaching  action  is  noticed. 

Experiment  114.  Reduction  of  telluric  acid.  To  a  solu- 
tion of  telluric  acid  prepared  in  the  previous  experiment 
add  a  little  potassium  bromide  and  sulphuric  acid,  and  boil. 
Note  the  evolution  of  bromine  and  the  reduction  to  tellu- 
rous  acid. 

Experiment  115.  Precipitation  of  tellurous  iodide,  (TeI4). 
To  a  solution  of  an  alkali  tellurite  add  sulphuric  acid  until 
the  precipitate  first  formed  dissolves.  Then  add  a  few 
drops  of  a  solution  of  potassium  iodide.  Note  the  black 
precipitate. 


H4  THE  RARER  ELEMENTS. 

Experiment  116.  Precipitation  of  elementary  tellurium. 
Try  the  action  of  the  following  reducing  agents  upon  sepa- 
rate portions  of  an  acid  solution  containing  tellurium: 
stannous  chloride,  hydrogen  sulphide,*  sulphurous  acid, 
magnesium,  and  acid  sodium  sulphite  (vid.  Experiment  109). 

Experiment  117.  Action  of  tellurium  compounds  before 
the  blowpipe.  Heat  on  charcoal  a  small  amount  of  a  tellu- 
rium compound.  Note  the  white  sublimate  and  the  green 
color  imparted  to  the  reducing  flame. 

Experiment  118.  Negative  test  of  tellurium.  Try  the 
action  of  ferrous  sulphate  upon  an  acidified  solution  of 
a  tellurite. 

SELENIUM,  Se,   79.1. 

Discovery.  For  some  time  previous  to  the  discovery 
of  selenium  a  red  deposit  had  been  noticed  in  the  lead 
chambers  used  in  the  manufacture  of  sulphuric  acid  at 
Gripsholm  in  Sweden.  The  deposit  was  present  when  the 
sulphur  employed  had  been  prepared  from  pyrites  from 
Fahlun,  Sweden,  but  was  seldom  observed  when  the  sulphur 
had  been  obtained  from  other  sources.  At  first  the  un- 
known substance  was  supposed  to  be  sulphur.  When  it 
was  burned,  an  odor  as  of  decayed  cabbage  was  given  off, 
and  this  was  supposed  to  be  caused  by  the  presence  of 
tellurium  sulphide,  although  no  tellurium  could  be  ex- 
tracted from  the  material.  In  1817  Berzelius,  having 
become  a  shareholder  in  the  acid  works,  examined  the 
red  deposit,  and  in  a  short  time  he  announced  the  dis- 
covery of  a  new  element.  Because  of  its  frequent  associa- 
tion with  tellurium,  and  its  many  points  of  similarity  to 
that  element,  he  named  it  Selenium,  from  aehrjvrf,  the 
moon  (Annal.  der  Phys.  u.  Chem.  (1818)  xxix,  229). 

*  Some  authors  give  TeS2  as  the  constitution  of  the  precipitate  by  hy- 
drogen sulphide. 


SELENIUM. 


Occurrence.     Selenium    is    found    usually    in    combina- 
tion with  the  metals,  as  in  the  following  minerals: 


Clausthalite,  PbSe, 
Tiemannite,  HgSe, 
Guana juatite,  Bi2Se3, 
Naumannite,  (Ag2,Pb)Se, 
Berzelianite,  Cu2Se, 
Lehrbachite,  PbSe  -  HgSe, 
Eucairite,  Cu2Se-Ag2Se, 
Zorgite,  vid.  Clausthalite, 
Crookesite,  (Cu,Tl,Ag)2Se, 
Onofrite,  Hg(S,Se), 
Galenobismutite,  PbBi2S4, 
Durdenite,  Fe2(TeO3)3-4H2O, 
Chalcomenite,  CuSeO3  •  2H20, 
Tellurium  (native),  Te, 
Selen-sulphur,  #Se-;yS, 
Selen-tellurium,  3Te-2Se, 


contains 27-28%  Se 

"    25-29% " 

"    24-34% " 

"    27-30%  •• 

"        39-40%  " 

"        24-28%  " 

"       31-32%  " 

29-34%  " 

"       .' 30-33%  " 

"        4-  6%   " 

"       0-14%  " 

"       i-  2%SeO, 

"       48-49%     " 

"      6-  7%Se 

"      35-66%  " 

"      29-30%  " 


Extraction.     Selenium  salts  may  be  extracted  from  flue- 
dust  by  the  following  methods: 

(1)  The    soluble,  material    is    dissolved    by   treatment 
with  water,  and  the  selenium  is  extracted  from  the  residue 
by  aqua  regia  (Berzelius,  vid.  Experiment  119). 

(2)  The  seleniferous  material  is  digested  with  a  solu- 
tion of  potassium  cyanide  at  a  temperature  of  8o°-ioo°  C. 
until  the  red  color  has  changed  to  gray,  (KSeCN).     The 
selenium  goes  into  solution  and  may  be  precipitated  by 
hydrochloric    acid    (Pettersson,    Ber.    Dtsch.    chem.    Ges. 

vii,    1719)- 

(3)  The  flue-dust  or  mineral  is  fused  with  sodium  car- 
bonate, and  the  selenium  is  extracted  with  water  as  sodium 
selenide  and  selenite,   (Na2Se;  Na2SeO3). 


Ii6  THE  RARER  ELEMENTS. 

The  Element.  A.  Preparation.  Selenium  in  the  ele- 
mentary condition  may  be  prepared  by  the  action  (i)  of 
sulphur  dioxide,  zinc,  or  iron,  upon  selenious  acid  (Ber- 
zelius) ;  (2)  of  hydrochloric  acid  upon  sodium  seleno-sul- 
phite  (Pettersson) ;  (3)  of  potassium  iodide,  sodium  thio- 
sulphate,  etc.,  upon  selenious  acid. 

B.  Properties.  Like  sulphur,  selenium  is  known  in 
several  allotropic  modifications,*  and  may  be  either  soluble 
or  insoluble  in  carbon  disulphide.  In  soluble  form  selen- 
ium is  a  red  powder  which  softens  at  5o°-6o°  C.,  is  partly 
fluid  at  100°  C.  and  is  completely  fused  at  250°  C  .  After 
it  has  been  melted  it  remains  in  a  plastic  condition  for  a 
long  time  and  has  a  metallic  luster.  Its  specific  gravity 
is  4.2  to  4.3.  From  a  warm  solution  in  carbon  disulphide 
the  element  separates  in  red,  monoclinic,  crystalline  plates, 
and  from  a  cold  solution  in  orange-red  monoclinic  crys- 
tals of  different  type.  The  specific  gravity  of  these  crys- 
talline varieties  is  4.4  to  4.5.  Selenium  insoluble  in  carbon 
disulphide  may  be  obtained  by  allowing  the  element  to 
cool  very  slowly  after  it  has  been  heated  to  a  higher  tem- 
perature than  130°  C.,  or  by  allowing  the  oxygen  of  the 
air  to  act  upon  selenides  in  aqueous  solution.  Under 
these  conditions  the  element  assumes  the  so-called  metallic 
form,  crystallizes  in  steel-gray  hexagonal  crystals,  and 
becomes  isomorphous  with  tellurium.  Metallic  selenium 
melts  at  217°  C.  without  previous  softening.  Its  specific 
gravity  is  4.8. 

Selenium  boils  at  700°  C.,  yielding  a  dark-yellow  vapor 
which,  when  condensed  and  cooled,  assumes  a  form  similar 
to  flowers  of  sulphur;  this  is  called  flowers  of  selenium. 
The  element  is  soluble  in  sulphuric  acid,  giving  a  green  solu- 
tion, and  is  oxidized  by  nitric  acid  to  selenious  acid,  (H2SeO3) . 

*  For  a  recent  discussion  of  these  modifications  see  Saunders,  Jour.  Phys. 
Chem.  (1900)  iv,  423. 


SELENIUM.  117 

It  combines  with  metals  to  form  selenides.  When  heated 
in  air  or  oxygen*  it  burns  with  a  blue  flame  and  goes  over 
to  the  dioxide,  (SeO2).  It  is  a  poor  conductor  of  heat  and 
electricity. 

Compounds.     A.  Typical  forms.      The    following    com- 
pounds of  selenium  may  be  considered  typical: 

Oxides SeO2       SeO8 

Chlorides Se2Cl2         SeCl4 

SeCl3Br 

Oxychloride SeOCl, 

Bromides Se2Br2        SeBr4 

SeClBr, 

Iodides Se2I2          SeI4 

Seleno-sulphite SeSO, 


Alums RjAl2(SeO4)4  +  24H2O 

Thioselenic  acid.  . .  H2SSeO3 

Thioseleniate K2SSeOs 

Cyanides (CN)2Se 

(CN)2Ses 

H(CN)Se 

K(CN)Se 

R(CN)Se2 

Nitride N2Se 

Phosphides P4Se3 

Selenides H2Se 

NiSe 

Ag2Se 

K2Se,  etc. 
Acids  (selenious  and  selenic)    HljSeOj  H2SeO4 


Salts  (selenites  and  seleniates)  R^SeOg   R2SeO4 

B.  Characteristics.     The  compounds  of  selenium  closely 
resemble  those  of  tellurium,  both  in  structure  and  in  behavior 


n8  THE  RARER  ELEMENTS. 

toward  reagents.  They  are,  however,  rather  more  sensi- 
tive to  the  act 'on  of  reducing  agents,  and  readily  precipitate 
the  red,  amorphous  variety  of  the  element,  which  tends  to 
become  black  when  heated.  Hydrogen  selenide  is  a  gas 

which  acts  like  hydrogen  sulphide  and  hydrogen  telluride, 

i 
and  precipitates  the  selenides  (R2Se).     By  the  treatment 

of  elementary  selenium  with  nitric  acid  or  aqua  regia 
and  evaporation  to  dryness,  selenious  oxide,  (Se02),  is 
formed,  which  dissolves  in  water,  forming  selenious  acid,, 
(H2SeO3).  By  the  action  of  powerful  oxidizing  agents, 
such  as  chlorine,  bromine,  or  potassium  permanganate , 
selenious  acid  may  be  oxidized  to  selenic  acid,  (H2SeO4), 

which  is  not  reduced  by  sulphur  dioxide.     These  acids 

i  i 

form  salts  of  the  types  R2SeO3  and  R2SeO4.     By  the  action 

of  reducing  agents,  such  as  sulphur  dioxide  or  ferrous 
sulphate,  red  amorphous  selenium  may  be  readily  pre- 
cipitated from  selenious  acid.  Two  chlorides,  (Se2Cl2; 
SeCl4),  and  the  corresponding  bromides  and  iodides  are 
known.  When  selenium  is  heated,  a  characteristic,  pene-' 
trating  odor  is  given  off  which  has  been  variously  described 
as  like  that  of  garlic,  decayed  cabbage,  and  putrid  horse- 
radish. This  odor  is  caused  by  the  formation  of  small 
amounts  of  the  hydride. 

Estimation.  A.  Gravimetric.  Selenium  is  generally 
weighed  as  the  element,  obtained  by  treating  solutions 
of  its  compounds  (i)  with  sulphurous  acid  in  hydrochloric 
acid  solution;  (2)  with  potassium  iodide  in  acid  solution 
(Peirce,  Amer.  Jour.  Sci.  [4]  i,  416);  (3)  with  hypophos- 
phorus  acid  in  alkaline  solution  (Gutbier  and  Rohn,  Zeitsch. 
anorg.  Chem.  xxxiv,  448).  Other  reducing  agents  may  be 
used. 

B.  Volumetric.  Selenium  may  be  determined  volu- 
metrically  (i)  by  oxidizing  selenious  acid  to  selenic  by 
means  of  standard  potassium  permanganate  in  sulphuric 
acid  solution,  using  an  excess  of  permanganate,  and  titrat- 


SELENIUM.  119 

ing  back  with  oxalic  acid  (Gooch  and  demons,  Amer. 
Jour.  Sci.  [3]  L,  51)  ;  (2)  by  reducing  selenic  or  selenious  acid 
by  means  of  potas  ium  iodide  in  hydrochloric  acid  solution, 


and  determining  by  appropriate  means  the  iodine  set  free 
(Muthmann  and  Schaefer,  Ber.  Dtsch.  chem.  Ges.  xxvi, 
1008;  Gooch  and  Reynolds,  Amer.  Jour.  Sci.  [3]  L,  254); 
(3)  by  reducing  selenic  acid  to  selenious  by  boiling  with 
hydrochloric  acid,  (SeO3  +  2HCl  =  SeO2  +  H2O  +  Cl2),  then 
passing  the  free  chlorine  into  potassium  iodide,  and  deter- 
mining the  iodine  set  free  (Gooch  and  Evans,  Amer.  Jour. 
Sci.  [3]  L,  400)  ;  (4)  by  employing  potassium  bromide  and 
sulphuric  acid  instead  of  hydrochloric  acid  in  (3)  (Gooch 
and  Scoville,  Amer.  Jour.  Sci.  [3]  L,  402)  ;  (5)  by  boiling 
a  solution  of  selenious  acid  with  sulphuric  acid,  a  known 
amount  of  potassium  iodide,  and  an  excess  of  arsenic  acid; 
the  reduction  of  the  selenious  acid  will  decrease  the  reduction 
of  arsenic  acid;  the  quantity  of  arsenious  acid  present  at 
the  close  of  the  action  may  be  measured,  after  neutral- 
ization with  potassium  bicarbonate,  by  standard  iodine 
(Gooch  and  Peirce,  Amer.  Jour.  Sci.  [4]  i,  31);  (6)  by  the 
reduction  of  selenious  acid  to  elementary  selenium  by 
means  of  standard  sodium  thiosulphate  solution  in  excess 
in  the  presence  of  hydrochloric  acid,  —  the  excess  of  thio- 
sulphate being  determined  by  standard  iodine  solution 
(Norris  and  Fay,  Amer.  Chem.  Jour,  xvm,  703  ;  Norton, 
Amer.  Jour.  Sci.  [4]  vn,  287)  ;  (7)  by  boiling  elementary 
selenium  with  ammonia  and  standard  silver  nitrate  solution, 
acidifying  with  nitric  acid,  and  determining  the  excess 
of  silver  nitrate  by  ammonium  sulpho-cyanide,  with  ferric 
alum  as  indicator;  the  quantity  of  selenium  present  is 
calculable  from  the  quantity  of  silver  nitrate  used,  as  is 
shown  in  the  following  equation:  4AgNO3  +  3Se  +  3H2O 
=  2Ag2Se  +  H2SeO3  +  4HNO3  (Friedrich,  Zeitsch.  angew. 
Chem.  xv,  852). 


120  THE  RARER  ELEMENTS. 

Separation.  Selenium  is  separated,  together  with  tel- 
lurium, from  other  elements  by  methods  given  under 
Tellurium.  Methods  of  accomplishing  the  separation  of 
these  two  elements  from  each  other  have  also  been  de- 
scribed. 


EXPERIMENTAL  WORK  ON  SELENIUM. 

Experiment  119.  Extraction  of  selenium  from  (i)  flue- 
dust  and  (2)  seleniferous  residues  from  the  electrolytic  refining 
of  copper,  (i)  Treat  about  25  grm.  of  the  washed  flue- 
dust  with  aqua  regia  as  long  as  any  evidence  of  action  is 
observed,  and  evaporate  to  dryness.  Extract  the  residue 
with  about  25  cm.3  of  strong  common  hydrochloric  acid, 
and  filter.  To  the  filtrate  add  about  a  gram  of  dry  ferrous 
sulphate,  and  warm  gently  if  necessary.  Filter  off  the  red 
amorphous  selenium. 

(2)  To  free  the  selenium  obtained  in  Experiment  109 
from  the  excess  of  tellurium  present  (a)  treat  the  material 
with  hydrochloric  acid  and  either  a  little  chlorine  or  a  drop 
of  nitric  acid.  Precipitate  the  selenium  by  ferrous  sulphate. 
(6)  Or  warm  the  material  with  a  dilute  solution  of  potassium 
cyanide.  The  selenium  goes  into  solution  as  potassium 
seleno-cyanide  and  may  be  precipitated  by  acidifying  the 
solution  with  hydrochloric  acid. 

Experiment  120.  Preparation  of  selenium  dioxide,  (SeO2). 
To  a  small  amount  of  elementary  selenium  add  nitric 
acid  until  the  oxidation  is  shown  to  be  complete  by 
the  cessation  of  the  evolution  of  red  fumes  (oxides  of 
nitrogen).  Evaporate  to  dryness  and  warm  gently.  The 
white  residue  is  selenium  dioxide.  Dissolve  this  in  a  little 
water  to  form  selenious  acid,  (H2SeO3). 

Experiment  121.  Precipitation  of  barium  selenite, 
(BaSeO3).  To  a  little  selenious  acid  add  a  few  drops  of 


EXPERIMENTAL   WORK  ON  SELENIUM.  121 

a  barium  salt  in  solution.  Test  the  action  of  hydro- 
chloric acid  upon  the  precipitate. 

Experiment  122.  Formation  of  selenic  acid,  (H2SeOJ. 
To  a  few  cm.3  of  selenious  ac  d  add  first  a  small  amount 
of  sulphuric  acid  and  then  a  solution  of  potassium  per- 
manganate until  the  purple  color  is  permanent.  Bleach 
by  the  careful  addition  of  oxalic  acid. 

Experiment  123.  Reduction  of  selenic  acid  to  selenious. 
Add  to  a  given  volume  of  selenic  acid  half  as  much  strong 
hydrochloric  acid  and  boil  to  about  two  thirds  of  the  total 
volume.  Note  the  evolution  of  chlorine.  Test  by  starch 
iodide  paper. 

Experiment  124.  Precipitation  of  elementary  selenium. 
Try  the  action  of  the  following  reducing  agents  upon  dilute 
selenious  acid:  sulphur  dioxide,  hydrogen  sulphide,  acid 
sodium  sulphite,  potassium  iodide,  stannous  chloride, 
ferrous  sulphate. 

Experiment  125.  Solvent  action  of  carbon  disulphide 
upon  selenium.  To  a  little  dry,  washed,  amorphous  selen- 
ium add  carbon  disulphide.  Filter,  and  allow  the  filtrate 
to  evaporate. 

Experiment  126.  Solvent  action  of  potassium  cyanide 
upon  selenium.  To  a  small  amount  of  the  red  amorphous 
selenium  add  a  few  cm.3  of  a  dilute  solution  of  potassium 
cyanide  (poison!),  warm  gently,  and  filter.  To  the  filtrate 
add  hydrochloric  acid. 

Experiment  127.  Behavior  of  selenium  when  subjected 
to  heat.  Heat  a  small  amount  of  elementary  selenium  on 
a  glass  rod.  Note  the  odor,  and  the  color  of  the  flame. 

Experiment  128.  Action  of  strong  sulphuric  acid  upon 
selenium.  To  a  small  amount  of  elementary  selenium  add 
a  few  cm.3  of  strong  sulphuric  acid  and  warm.  Note  the 
color.  Compare  with  tellurium  (vid.  Experiment  no). 


122  THE  RARER  ELEMENTS. 

PLATINUM,   Pt,   194.8. 

Discovery.  In  the  year  1750  William  Watson  presented 
to  the  Royal  Society  a  communication  from  William 
Brownrigg  in  which  was  described  a  "  semi-metal  called 
Platina  di  Pinto ' '  found  in  the  Spanish  West  Indies.  Wat- 
son stated  that,  so  far  as  he  knew,  no  previous  mention  had 
been  made  of  this  substance  except  by  Don  Antonio  de 
Ulloa  in  the  history  of  his  voyage  to  South  America,  pub- 
lished in  Madrid  in  1748  (Phil.  Trans.  Roy.  Soc.  (1750) 
XLVI,  584).  However,  an  earlier  discovery  is  suggested  by 
a  statement  of  Scaliger  in  1558,  who,  in  combating  the 
opinion  of  Cardanus,  that  all  metals  are  fusible,  declared 
that  an  infusible  metallic  substance  existed  in  the  mines  of 
Mexico  and  Darien.  As  platinum  is  found  in  those  coun- 
tries, it  is  probably  the  metal  referred  to  The  name 
Platinum  is  derived  from  the  Spanish  platina,  the  diminu- 
tive of  plata,  silver. 

Occurrence.  Platinum  occurs  alloyed  with  the  various 
metals  of  its  group — palladium,  osmium,  iridium,  etc. — and 
associated  with  other  metals,  as  iron,  lead,  copper,  titanic 
iron,  etc.  It  is  found  chiefly  in  the  Ural  Mountains,  but 
also  in  Brazil,  Mexico,  Borneo,  California,  North  Carolina, 
and  elsewhere.  It  comprises  from  fifty  to  eighty  per  cent, 
of  the  alloys  in  which  it  occurs.  Platinum  is  found  com- 
bined in  the  mineral  sperrylite,  PtAs2,  which  contains  about 
fifty-three  per  cent,  of  the  metal. 

Extraction.  Platinum  may  be  extracted  from  its  alloys 
by  the  following  methods: 

(i)  Fusion  process.  The  material  is  fused  with  sul- 
phide of  lead.  The  iron  present  combines  with  the  sul- 
phur. The  platinum  alloys  with  the  lead,  while  the  os- 
mium and  iridium  do  not.  The  lead-platinum  alloy  is 
separated  from  the  mass  and  cupelled.  The  platinum  is 
left  (Deville  and  Debray). 


PLATINUM.  123 

(2)  Wet  process.  The  pulverized  alloy  is  heated  in  a 
porcelain  dish  with  aqua  regia  as  long  as  action  continues. 
The  solution  obtained  is  nearly  neutralized  with  calcium 
hydroxide,  and  the  iron,  copper,  rhodium,  iridium,  and  part 
of  the  palladium  separate.  After  the  removal  of  these,  the 
nitrate  is  evaporated  to  dryness  and  the  residue  is  ignited 
and  treated  with  water  and  hydrochloric  acid.  The  plati- 
num, with  traces  of  the  platinum  metals,  remains. 

The  Element.  A.  Preparation.  As  extracted  from  its 
alloys,  platinum  is  in  the  elementary  condition  (vid.  Ex- 
traction). 

B.  Properties.  In  its  usual  form,  elementary  platinum 
is  a  grayish-white  metal  which  is  very  malleable  and 
ductile,  but  fusible  only  in  the  oxy hydrogen  blowpipe  or 
by  means  of  the  electric  current.  At  no  temperature  is  it 
oxidized  by  water  or  oxygen,  or  attacked  by  the  simple 
acids.  It  is  soluble,  however,  in  aqua  regia.  Platinum  is 
not  acted  upon  by  sulphur  alone,  but  if  alkalies  are  present 
with  the  sulphur  some  action  takes  place.  It  is  attacked 
also  when  heated  with  potassium  nitrate.  Its  specific 
gravity  is  21.48. 

Besides  the  ordinary  form,  the  element  platinum  is 
known  to  exist  in  two  allotropic  conditions:  (i)  spongy 
platinum,  obtained  by  the- ignition  of  ammonium  chloro- 
platinate,  and  (2)  platinum-black,  obtained  by  reducing 
acid  solutions  of  platinum  salts.  In  both  of  these  forms 
platinum  condenses  gases  on  its  surface. 

Compounds.  A.  Typical  forms.  The  following  may  be 
regarded  as  typical  compounds  of  platinum : 

Oxides PtO  Pt3O4  PtO2  v 

Chlorides PtCl2  PtCl4 

Double  chlorides PtCl2-SrCl2+  PtCl4  •  2AgCl,  etc. 

6H2O,  etc. 

Bromides PtBr2  PtBr4 

Double  bromides PtBr2-2KBr,  etc.  PtBr4  •  SrBr2-f  ioH2O 

Iodides PtI2  PtI4 


124  THE  RARER  ELEMENTS. 

Double  iodides PtI4  •  2KI,  etc. 

Fluorides PtF3  PtF4 

Sulphides PtS  *       PtS2 

Oxysulphide PtOS 

Sulpho  salts R2PtS6 

Sulphites PtSO3  •  R2SO3 ;  PtSO3  •  2RC1 

Nitrites R2(NO2)4Pt 

lodonitrites R2(NO2)2I2Pt 

Cyanide Pt(CN)a 

Hydro  -  platino  -  cyanic 

acid H2Pt(CN)4 

Platino-cyanides R2Pt(CN)4;  RPt(CN)4,  typical 

Chloroplatinic  acid.  .  .  .  H2PtCl<, 

Chloroplatinates RaPtCl,,;  RPtCl.,  typical 

B.  Characteristics.  The  compounds  of  platinum  may 
be  divided  into  two  classes,  of  which  the  platinous  and 
platinic  oxides,  (PtO;  PtO2),  serve  as  types.  The  salts  of 
the  lower  condition  of  oxidation  are  usually  colorless  or 
reddish  brown;  they  give  with  hydrogen  sulphide  or  am- 
monium sulphide  a  dark-brown  precipitate  of  platinous 
sulphide,  (PtS),  which  is  soluble  in  ammonium  sulphide. 
They  are  decomposed  at  red  heat,  and  are  slowly  reduced 
to  metallic  platinum  when  boiled  with  ferrous  sulphate. 
The  salts  of  the  higher  condition  of  oxidation  have  a  yellow 
or  brown  color,  and  like  the  platinous  salts  they  are  de- 
composed at  red  heat.  Metals  in  general  and  organic 
matter  precipitate  platinum  from  solutions  of  platinic 
salts.  The  brownish-gray  platinic  sulphide,  (PtS2),  is  pre- 
cipitated by  the  action  of  hydrogen  sulphide  upon  a  solu- 
tion of  chloroplatinic  acid,  (H2PtCl6) ;  this  sulphide  dissolves 
slowly  in  ammonium  sulphide.  Salts  of  potassium  and 
ammonium  act  upon  chloroplatinic  acid  precipitating  the 

corresponding  salts  of  that  acid,  (R2PtCl6) .     When  platinous 
chloride  dissolves  in  potassium  cyanide,  platinum  potas- 


PLATINUM.  125 

sium  cyanide  is  formed,  (K2Pt(CN)4  +  4H2O).     Many  salts 

of  this  type  are  known. 

The  platinum-ammonium  compounds  comprise  a  large 

number  of  complex  salts  of  the  following  types: 

(a)  The      platosamines,       PtR2(NH3)4;       PtR2(NH3)3; 

PtRjCNHjV,     PtR2(NH3);     and      (6)    the     platinamines, 

PtR4(NH3)4;  PtR4(NH3)3;  PtR4(NH3)2;  PtR4(NH3). 

In  the  above  formulae  R  may  stand  for  OH,  Cl,  Br,  I, 

or  NO3.     These  compounds  are  formed  by  the  action  of 
ammonia  upon  the  platinum  salts. 

Potassium  iodide  gives  a  red-brown  color  to  very  dilute 
solutions  of  platinum  salts. 

Estimation.  A.  Gravimetric.  Platinum  is  generally 
weighed  as  the  metal,  obtained  (i)  by  precipitation  from 
solutions  of  compounds  by  means  of  appropriate  reducing 
agents,  such  as  formic  acid,  alcohol  in  alkaline  solution,  or 
magnesium  (Atterberg,  Chem.  Ztg.  xxn,  538) ;  (2)  by  pre- 
cipitation of  the  sulphide  and  ignition;  (3)  by  precipitation 
of  ammonium  or  potassium  chloroplatinate,  and  decomposi- 
tion by  heat  into  the  metal  and  the  volatile  or  soluble 
alkali  chloride. 

B.  Volumetric.  Platinum  may  be  estimated  volumet- 
rically  by  reducing  the  tetrachloride  by  means  of  potas- 
sium iodide,  (PtCl4  +  4KI=PtI2  +  I2  +  4KCl)>  and  determin- 
ing by  standard  sodium  thiosulphate  the  iodine  thus  liber- 
ated (Peterson,  Zeitsch.  anorg.  Chem.  xix,  59). 

Separation.  ,  From  most  other  elements  platinum  may 
be  separated  by  the  action  of  reducing  agents  in  precipitat- 
ing the  metal  from  solutions.  From  the  metals  with  which 
it  is  most  often  found  associated  it  may  be  separated  by 
the  following  methods:  from  gold  (i)  by  the  action  of 
ammonium  chloride  upon  the  chlorides,  ammonium  chloro- 
platinate being  precipitated;  (2)  by  the  action  of  hydro- 
gen dioxide  and  sodium  hydroxide  upon  cold  solutions, 
the  gold  being  precipitated  (Vanino  and  Seeman,  Ber.  Dtsch. 


126  THE  RARER  ELEMENTS. 

chem.  Ges.  xxxn,  1968) ;  (3)  by  the  action  of  oxalic  acid  or 
ferrous  salts,  gold  being  again  precipitated  (Hoffmann  and 
Kriiss,  Zeitsch.  anal.  Chem.  xxvu,  66;  Bettel,  Chem.  News 
LVI,  133) ;  from  silver  by  heating  the  metals  with  concen- 
trated sulphuric  acid,  silver  dissolving  (Richards,  The 
Analyst,  xxvu,  265) ;  from  mercury  by  ignition  of  the 
metals,  mercury  being  volatilized. 

The  separation  of  platinum  from  the  other  platinum 
metals  is  so  involved  with  the  separation  of  these  from 
each  other  that  the  whole  subject  will  be  briefly  considered 
in  this  place.  The  following  methods  have  been  suggested, 
(i)  The  ore  is  first  treated  with  chlorine  water,  which  ex- 
tracts the  gold,  then  with  dilute  aqua  regia,  which  dis- 
solves the  platinum,  palladium,  and  rhodium.  From  this 
solution  the  platinum  is  precipitated  by  ammonium  chloride 
and  alcohol;  and  from  the  filtrate,  after  neutralization  with 
sodium  carbonate,  the  palladium  is  precipitated  as  the 
cyanide  by  mercury  cyanide.  The  residue  from  the  aqua 
regia  treatment,  containing  osmium,  iridium,  and  ruthe- 
nium, is  heated  in  air.  Osmium  is  volatilized  as  the  tetrox- 
ide,  ruthenium  sublimes  as  the  dioxide,  and  iridium  is 
left  (Pirngniber,  J.  B.  (1888),  2560;  Wyatt,  Eng.  and  Min. 
J.  XLIV,  273).  (2)  A  neutral  or  acid  solution  of  the  plat- 
inum metals,  gold,  and  mercury,  containing  chlorine,  is 
treated  with  dilute  nitric  acid  and  heated  to  boiling  in  a 
retort ;  osmic  tetroxide  distils.  The  solution  is  cooled,  and 
shaken  with  ether,  which  withdraws  the  chloride  of  gold. 
After  the  removal  of  the  ether  and  gold  by  means  of  a 
separating  funnel  the  remaining  solution  is  treated  with 
ammonium  acetate  and  boiled  with  formic  acid.  This 
treatment  precipitates  all  the  metals,  which  are  then  heated 
in  a  current  of  hydrogen  to  volatilize  the  mercury.  The 
remaining  metals  are  mixed  with  sodium  chloride  and 
heated  with  moist  chlorine,  and  the  mass  is  extracted  with 
water.  If  there  is  any  residue  at  this  point  it  will  probably 


PLATINUM.  127 

be  found  to  be  indium,  and  ruthenium.  The  solution  is 
treated  with  concentrated  ammonium  chloride  as  long  as 
any  precipitate  forms.  This  precipitate  consists  of  the 
double  chlorides  of  ammonium  with  platinum,  iridium,  and 
ruthenium  respectively,  palladium  and  rhodium  remaining 
in  solution.  The  precipitate  is  dissolved  in  warm  water 
and  treated  with  hydroxylamine,  which  reduces  the  irid- 
ium and  ruthenium  to  the  condition  of  the  sesquichlorides ; 
upon  the  addition  of  ammonium  chloride  platinum  is  pre- 
cipitated as  the  chloroplatinate.  The  hydroxylamine  fil- 
trate is  evaporated,  the  residue  is  heated  in  the  presence  of 
hydrogen  and  fused  with  potassium  hydroxide  and  nitrate, 
the  mass  is  cooled  and  extracted  with  water.  Ruthenium 
dissolves  as  potassium  ruthenate,  (K2RuO4),  and  iridium 
remains  as  the  hydrate,  (Ir(OH)3).  The  solution  contain- 
ing rhodium  and  palladium  is  evaporated  slowly  to  dryness 
in  the  presence  of  an  excess  of  ammonia,  and  the  residue 
is  dissolved  in  the  smallest  possible  amount  of  a  warm,  dilute 
ammoniacal  solution.  Upon  cooling,  the  rhodium  separates 
as  a  complex  chloride,  (Rh(NH3)5Cl3),  and  the  palladium 
remains  in  solution  (Mylius  and  Dietz,  Ber.  Dtsch.  chem. 
Ges.  xxxi,  3187).  (3)  Gold  is  removed  by  means  of  dilute 
aqua  regia.  By  treatment  with  concentrated  aqua  regia 
platinum,  palladium,  rhodium,  ruthenium,  and  part  of  the 
iridium  are  then  dissolved,  while  an  insoluble  alloy  of  os- 
mium and  iridium  in  the  form  of  grains  or  plates  remains. 
This  alloy  is  mixed  with  sodium  chloride  and  the  mixture 
is  heated  in  a  tube  with  chlorine.  Osmium  tetroxide, 
(OsO4),  distils,  and  sodium-iridium  chloride,  (Na2IrCl6),  re- 
mains (Wohler,  Pogg.  Annal.  xxxi,  161).  To  the  solution  of 
the  other  platinum  metals  in  aqua  regia  ammonium  chloride. 
is  added.  The  precipitate,  consisting  of  the  double  salts  of 
platinum  and  iridium,  may  by  ignition  be  converted  intq 
iridium-bearing  platinum  sponge  (used  in  the  manufacture 
of  platinum  vessels) .  To  the  filtrate  iron  or  copper  is  added, 


128  THE  RARER  'ELEMENTS. 

which  throws  down  .the  palladium,  rtiodium,  and  ruthenium 
as  a  metallic  powder.  From  this  mixture  palladium  and 
the  iron  or  copper  are  dissolved  by  nitric  acid,  and  the  solu- 
tion is  then  shaken  with  mercury,  which-  removes  the  palla- 
dium (von  Schneider,  Liebig  Annal.  v,  264,  suppl.).  The 
mixture  of  rhodium  and  ruthenium  remaining  is  heated  with 
sodium  chloride  at  low  redness  in  a  current  of  chlorine  and 
the  mass  is  extracted  with  water.  This  liquid  is  boiled 
with  potassium  nitrite  and  "enough  potassium  carbonate 
to  make  the  solution  faintly  alkaline.  It  is  then  evaporated 
to  dryness  and  the  residue  is  pulverized  and  extracted 
with  absolute  alcohol.  The  rhodium  remains  undissolved 
as  a  double  nitrite  of  potassium  and  rhodium,  (K6Rh2(NO2)12, 
while  the  ruthenium  dissolves,  also  as  a  double  nitrite  with 
potassium,  (Ru(NO2)6-6KNO2). 

Platinum  may  be  separated  from  palladium  (i)  by  the 
action  of  warm  dilute  nitric  acid  upon  the  metals,  palladium 
dissolving;  (2)  by  the  action  of  a  strong  solution  of  am- 
monium chloride  and  alcohol  upon  the  double  potassium 
salts,  the  palladium  salt  being  soluble  (Cohn  and  Fleissner, 
Ber.  Dtsch.  chem.  Ges.  xxix,  R.  876);  from  iridium  (i)  by 
electrolysis,  the  platinum  being  precipitated  (Smith,  Amer. 
Chem.  Jour,  xiv,  435) ;  (2)  by  the  action  of  potassium 
nitrite,  sodium  carbonate,  and  boiling  water  upon  the 
double  potassium  salts,  iridium  being  reduced  to  the  con- 
dition of  the  sesquichloride  and  dissolved  (Gibbs,  Amer. 
Jour.  Sci.  [2]  xxxiv,  347) ;  from  osmium  by  heating  in  the 
presence  of  oxidizing  material,  osmium  tetroxide  being 
formed  and  volatilized ;  from  ruthenium  by  treating  potas- 
sium chloroplatinate  and  the  corresponding  ruthenium 
salt  with  cold  water  >  ;the  ruthenium  salt  dissolving  (Gibbs, 
loc.  tit.)',  from  rhodium  (i)  by  the  method  described  for 
the  separation  from  ruthenium;  or  (2)  by  the  action  of 
concentrated  solutions*  of  the  alkali  chlorides  upon  these 
salts,  the  rhodium  dissolving  (Gibbs,  loc.  tit.). 


EXPERIMENTAL    WORK  ON  PLATINUM.  129 

< 

EXPERIMENTAL  WORK  ON. PLATINUM. 

Experiment  129.  Preparation  of  chloroplatinic  acid  from 
laboratory  residues.  •  Boil  the  residues  consisting  of  po- 
tassium chloroplatinate,  etc.,  with  a  solution  of  sodium 
carbonate  and  add  a  little  alcohol.  The  platinum  is  de- 
posited as  a  black  powder.  Wash  the  powder,  first  with 
hot  wrater,  then  with  hot  hydrochloric  acid;  dry  it,  dis- 
solve it  in  aqua  regia,  evaporate  the  liquid,  adding  a  little 
hydrochloric  acid  from  time  to  time  to  remove  the  nitric 
acid,  until  the  point  of  crystallization  is  reached. 

Experiment  130.  Precipitation  of  the  chloroplatinates 
of  ammonium,  potassium,  ccssium,  rubidium,  and  thallium, 

(R2PtCl6).  To  separate  portions  of  a  solution  of  chloro- 
platinic acid  add  salts  of  ammonium,  potassium,  caesium, 
rubidium,  and  -thallium  in  solution.  Note  the  compara- 
tive insolubility  of  the  new  compounds  in  water  and  in 
alcohol. 

Experiment  131.  Precipitation  of  platinic  sulphide, 
(PtS2).  To  a  solution  of  chloroplatinic  acid  add  a  little 
hydrogen  sulphide,  and  warm. 

Experiment  132.  Precipitation  of  elementary  platinum, 
(a)  To  a  solution  of  a  platinum  salt  add  sodium  carbonate 
to  alkaline  reaction;  add  also  a  few  drops  of  alcohol  and 
boil. 

(6)  Try  the  action  of  oxalic  acid  upon  a  platinum  salt  in 
solution. 

Experiment  133.  Action  of  acids  upon  platinum.  Try 
separately  the  action  of  strong  hydrochloric  and  nitric 
acids  upon  metallic  platinum.  Note  the  effect  of  a  mixture 
of  the  two  acids  upon  the  metal. 

Experiment  134.  Test  for  platinum  in  solution.  To  a 
very  dilute  solution  of  a  platinum  sarlt  free  from  chlorine 
add  a  small  crystal  of  potassium  iodide.  Note  the  color. 


13°  THE  RARER  ELEMENTS. 

THE  PLATINUM  METALS 

OTHER    THAN    PLATINUM. 

Occurring  almost  invariably  associated  with  platinum 
and  usually  alloyed  with  it  are  small  quantities  of  certain 
rare  elements  which,  together  with  platinum,  comprise 
the  group  of  so-called  Platinum  Metals.  These  very  rare 
elements  are  the  following: 

Palladium,   Pd,    106  Osmium,   Os,    191 

Iridium,  Ir,  193  Rhodium,  Rh,  103 

Ruthenium,  Ru,   101.7 

Discovery.  In  1803,  in  the  course  of  the  purification 
of  a  considerable  quantity  of  crude  platinum,  Wollaston 
isolated  a  new  metal  which  he  named  Palladium,  in  honor 
of  the  discovery  by  Olbers  of  the  planetoid  Pallas.  The  newly 
discovered  element  was  brought  to  the  attention  of  scien- 
tists anonymously  through  a  dealer's  advertisement,  which 
offered  "palladium  or  new  silver"  for  sale.  Much  dis- 
cussion as  to  the  nature  of  the  substance  ensued,  Chenevix, 
in  particular,  holding  it  to  be  an  alloy  of  platinum  and  mer- 
cury. In  1805  Wollaston  confessed  to  the  discovery  and 
naming  of  the  metal  (Phil.  Trans.  Roy.  Soc.  (1803)  xcm, 
290;  ibid.  (1805)  xcv,  316;  Nicholson 's  J.  (1805)  x,  204). 

The  same  year  that  palladium  was  discovered,  Smithson 
Tennant  found  that '  *  the  black  powder  which  remained  after 
the  solution  of  platina  did  not,  as- was  generally  believed, 
consist  chiefly  of  plumbago,  but  contained  some  unknown 
metallic  ingredients. "  In  1 804  he  presented  to  the  Royal 
Society  as  the  result  of  his  study  a  communication  announc- 
ing the  discovery  of  two  new  metals, -Iridium,  named '  *  from 
the  striking  variety  of  colors  which  it  gives  while  dissolving 
in  marine  acid, ' '  and  Osmium,  so  called  because  of  the 


THE  PLATINUM  METALS.  131 

penetrating  odor  (007*77,  odor)  of  the  acid  obtained  from 
the  oxidation  of  the  element  when  it  is  heated  in  a  finely 
divided  condition  (Phil.  Trans.  Roy.  Soc.  (1804)  xciv,  411). 

A  few  days  after  Tennant's  communication,  Wollaston 
announced  the  discovery  of  an  element  in  the  *  '  fluid  which 
remains  after  the  precipitation  of  platina  by  sal  ammoniac,  '  * 
and  suggested  the  name  Rhodium  (podios,  rose-like),  "from 
the  rose  color  of  a  dilute  solution  of  the  salts  containing 
it"  (Phil.  Trans.  Roy.  Soc.  (1804)  xciv,  419). 

In  1826  Osann  claimed  the  discovery  of  three  new  ele- 
ments in  platinum  alloys.  These  he  named  Ruthenium, 
Polinium,  and  Pluranium  (Pogg.  Annal.  vm,  505;  Amer. 
Jour.  Sci.  xvi,  384).  Later  he  withdrew  the  claim.  In 
1844  Claus  found  that  there  was  an  unknown  metal  in  the 
mixture  of  substances  which  had  been  called  by  Osann 
"ruthenium  oxide,"  and  for  it  he  retained  the  name 
ruthenium,  derived  from  Ruthenia,  i.e.  Russia,  where  the 
substance  was  first  found  (Pogg.  Annal.  LXIV,  192,  208; 
Amer.  Jour.  Sci.  XLVIII,  401). 

Occurrence.  The  very  rare  platinum  metals,  as  has 
been  already  stated,  are  found  in  general  in  platinum- 
bearing  material.  Palladium  and  iridium  sometimes  occur 
native;  the  others  always  in  alloys  or  in  combination. 


%  Ru 
Native  platinum  contains  0.1-3.1  traces-4  .  2        traces  o  .  2-3  .  4 


"       iridium 
Palladium  gold 
Iridosmine 
Laurite, 


Rhodium  gold 


0.4-0.8  27-76.8  circa  7 


5-10 


17-48  40.7     0.5-12.3  0.2-6 

circa  3  65 

34-43 


Extraction.  For  methods  of  extraction  of  the  very 
rare  platinum  metals  see  Extraction  and  Separation  of 
Platinum. 

The  Elements.  I.  PALLADIUM.  A.  Preparation.  Ele- 
mentary palladium  may  be  obtained  (i)  by  heating  the 
potassium  double  chloride  with  hydrogen  (Roessler) ;  (2)  by 


132  THE  RARER  ELEMENTS. 

heating  the  iodide  with  hydrogen;  and  (3)  by  heating  the 
chloride  or  cyanide. 

B.  Properties.  Palladium  is  a  ductile,  malleable,  white 
metal  which  looks  like  platinum.  It  may  be  partially 
oxidized  before  the ,  oxy hydrogen  blowpipe.  It  is  soluble 
in  strong  nitric,  hydrochloric,  and  sulphuric  acids,  and 
easily  soluble  in  aqua  regia.  It  fuses  at  a  lower  temperature 
than  any  other  of  the  platinum  metals.  In  spongy  form 
it  has  the  power  of  absorbing  gases.  Its  specific  gravity 
is  11.4-11.8.  Because  of  the  color  and  hardness  of  pal- 
ladium and  its  unalterability  in  the  air  it  is  used  for  the 
graduated  surfaces  of  fine  astronomical  instruments.  It 
may  be  distinguished  from  the  other  platinum  metals  by 
the  comparative  ease  with  which  it  dissolves  in  nitric  acid. 

II.  OSMIUM.      A.  Preparation.      The    element    osmium 
may  be  prepared  (i)  by  heating  the  amalgam  in  the  presence 
of  hydrogen  (Berzelius) ;  (2)  by  heating  the  sulphide  in  a 
closed  coke  crucible ;  (3)  by  passing  the  vapor  of  the  tetroxide 
mixed  with  carbon  dioxide  and  carbon  monoxide  through  a 
heated  porcelain  tube;   (4)  by  passing  the  vapor  of  the 
tetroxide  through  a  heated  porcelain  tube  containing  finely 
divided   carbon   (Deville    and    Debray);    (5)    by    igniting 
osmyldiamine   chloride,    (Os(NH3)402Cl2),  in  a   current   of 
hydrogen. 

B.  Properties.  Osmium,  the  heaviest  of  the  platinum 
metals,  is  a  bluish  substance,  crystals  of  which  are  harder 
than  glass.  In  the  compact  form  it  is  insoluble  in  all  acids 
and  in  aqua  regia,  and  is  rendered  soluble  only  by  fusion 
with  nitrates.  The  amorphous  modification  is  slowly 
soluble  in  nitric  acid  and  in  aqua  regia.  The  specific  gravity 
of  the  compact  and  amorphous  modifications  is  21.3;  of 
the  crystalline  form  22.4.  In  the  alloy  iridosmine  the 
element  is  employed  for  compass  bearings  and  for  the 
tips  of  gold  pens. 

III.  IRIDIUM.     A.  Preparation.     Metallic   iridium   may 


THE  PLATINUM  METALS.  133 

be  obtained  (i)  by  heating  iridium-ammonium  chloride, 
and  (2)  by  heating  indium-potassium  chloride  with  sodium 
carbonate. 

B.  Properties.  Iridium,  a  hard,  brittle  metal,  resembles 
silver  and  tin  in  appearance.  The  ignited  form  is  insoluble 
in  all  acids  and  in  aqua  regia.  The  element  is  partially 
oxidized,  however,  by  fusion  with  sodium  nitrate,  and  the 
fused  mass  may  be  dissolved  by  boiling  it  with  aqua  regia. 
In  spongy  form  iridium  has  the  specific  gravity  of  15.86; 
after  fusion  the  specific  gravity  is  21-22.  Elementary  iridium 
is  not  used  in  the  arts,  but  its  alloy  with  osmium,  as  stated 
above,  is  employed  for  compass  bearings  and  for  the  tips 
of  gold  pens;  its  alloy  with  platinum  is  used  in  the  manu- 
facture of  laboratory  vessels  and  for  standard  weights 
and  measures,  and  an  oxide  is  used  in  ehina-painting. 

IV.  RHODIUM.     A.  Preparation.      Elementary  rhodium 
may  be  prepared  (i)  by  heating  ammonium -rhodium  ses- 
quichloride;    (2)    by  heating   rhodium   sesquichloride  and 
sodium  in  a  current  of  hydrogen;  (3)  by  heating  rhodium 
sulphide  to  a  white  heat;   and  (4)   by  allowing  reducing 
agents,  as  formic  acid,  zinc,  iron,  alcohol  in  alkaline  solu- 
tion, hydrogen,  etc.,  to  act  upon  soluble  salts. 

B.  Properties.  Rhodium  is  a  grayish- white  metal  which 
has  the  appearance  of  aluminum.  When  pure  it  is  almost 
absolutely  insoluble  in  acids  and  in  aqua  regia,  but  when 
alloyed  it  may  be  dissolved  in  aqua  regia.  It  is  fusible 
before  the  oxyhydrogen  blowpipe,  but  more  difficultly 
than  platinum.  It  has  the  property  of  absorbing  hydrogen. 
Of  all  the  platinum  metals  rhodium  is  most  easily  attacked 
by  chlorine.  Its  specific  gravity  is  11-12.  The  alloy  of 
rhodium  with  steel  is  somewhat  used  in  the  arts. 

V.  RUTHENIUM.     A.  Preparation.     The  element  ruthe- 
nium may  be  obtained  (i)  by  heating  the  oxide  with  illu- 
minating-gas, and  (2)  by  heating  mthenium-ammonium- 
mercury  chloride. 


THE  RARER  ELEMENTS. 


B.  Properties.  Ruthenium  is  a  hard,  brittle  metal, 
dark  gray  to  black  in  color.  It  is  almost  completely  insolu- 
ble in  acids  and  in  aqua  regia;  and  osmium  alone,  of  all 
the  platinum  metals,  is  more  difficultly  fusible.  It  may 
be  slightly  oxidized  by  fusion  with  caustic  potash  and 
oxidized  to  a  greater  degree  by  fusion  with  potassium 
nitrate.  The  specific  gravity  of  the  crystalline  form  is 
12.26;  of  the  melted  form  11.4;  and  of  the  porous  form  8.6. 

Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  the  platinum  metals  may  be  considered  typical: 

Oxides Pd2O 

PdO 


Pd02 


Chlorides PdCl 

PdCl2 

PdCl4 
Bromides PdBr2 

PdBr4 
Iodides Pdl, 


OsO 

IrO? 

RhO 

RuO 

Os203 

Ir:03 

Rh203 

Ru2O3 

Os02 

IrO2 

Rh02 

RuO2 

(Os03)* 

(Ru03)* 

OsO4 

RuO4 

(Ru207)* 

OsCl2 

IrCl2 

RhCl2 

RuCl3 

OsCl, 

Ir2Cl8 

Rh2Cl8 

RuA, 

OsCl4 

IrCl4 

RuCl, 

Ir2Br6 

IrBr4 

Sulphides. . 


.Pd2S 
PdS 

PdS, 


Sulphates.  ....  ,PdSO4 


Sulphites PdSOj- 

3Na2S03 

Sulpho  salts.  .  .  .R2Pd3S4 
R2PdS3 


OsS2 
OsS4 

OsS03 


IrI4 

IrS 

Ir2S, 

IrS2 


Rh2I8 


RhS 
Rh2S3 


Rh2(S04)3 


Ir2(S03)8       Rh2(SOs)a 


Ru2S3 
RuS2 
RuS3 


*  This  oxide  is  known  only  in  combination. 


THE  PLATINUM    METALS. 


135 


Nitrites Pd(NO2)2-  2KNO2 


Nitrates 


Pd(NO3) 


Ir2(N02)8.     Rh2(N02V      Ru2(N02)fl. 
6HN02          6RNO2  6RNO2 


Acids  and  corre- 

spond'g  salts..  .  H2PdCl4  ; 

R2PdCl4 


H2PdCl8; 
R2PdCl0 


H.OSC1.; 

RsOsCl,, 
H2OsCl6; 

R2OsCle 


R4RhCl7; 
R3RhCl<, 


H2RuCl5 


R2IrCl« 


Characteristics.  I.  PALLADIUM.  The  compounds  of  pal- 
ladium resemble  those  of  platinum,  both  in  form  and 
in  general  characteristics.  As  in  the  case  of  platinum, 
palladium  combines  with  ammonia  to  form  complex  salts, 
and  an  oxide,  (PdO),  forms  salts  with  sulphur  dioxide  and 
with  nitrogen  trioxide,  (N2O3).  In  general  the  salts  are 
quite  easily  reduced  to  the  metal  by  heating ;  their  solutions 
resemble  a  solution  of  platinic  chloride  in  color.  Two 
oxides,  (PdO;  PdO2),  are  well  known,  of  which  the  lower 
forms  the  more  stable  compounds.  These  compounds  give 
a  yellowish-brown  precipitate  with  potassium  hydroxide. 
Solutions  of  palladium  salts  give  with  mercuric  cyanide  a 
yellowish- white  precipitate,  (Pd(CN)2) ;  with  potassium 
iodide  a  black  precipitate,  (PdI2),  which  is  soluble  in  excess 
of  the  reagent ;  and  with  hydrogen  sulphide  also  a  black 
precipitate,  (PdS),  insoluble  in  ammonium  sulphide. 
Mercuric  cyanide  and  potassium  iodide  are  often  used  as 
tests  for  palladium. 

II.  OSMIUM.  Compounds  of  osmium  are  known  in  five 
degrees  of  oxidation.  The  lowest  three  oxides,  (OsO; 
Os2O3;  OsO2),  are  basic  in  character,  the  fourth,*  (OsO3), 
is  acidic,  and  the  fifth,  (OsO4),  is  also  acidic,  but  it  forms 


*  Known  only  in  salts. 


136  THE  RARER  ELEMENTS. 

no  salts.     Three  chlorides,  (OsCl2 ;  OsCl3 ;  OsCl4) ,  are  known, 
corresponding  to  the  lowest  oxides.     The  metals  sodium, 

potassium,  and  barium  form  salts  of  the  type  R2OsO4. 
These  salts  are  readily  decomposed,  especially  by  acids,  and 
form  the  dioxide  and  the  tetroxide.  When  osmium  com- 
pounds are  heated  in  the  air  with  oxidizing  agents,  or  are 
melted  with  potassium  nitrate,  the  tetroxide  is  obtained. 
It  is  volatile  when  heated,  highly  corrosive,  and  disagree- 
able like  chlorine.  It  is  soluble  in  water  and  is  reduced 
by  reducing  agents.  From  potassium  iodide  it  frees  iodine, 
and  with  formic  acid  to  which  potassium  hydroxide  has 
been  added  it  gives  a  violet  color.  With  ferrous  sulphate 
it  precipitates  black  osmium  hydroxide,  (Os(OH)4),  and 
with  hydrogen  sulphide  it  brings  down  the  brownish-black 
sulphide  (OsS4),  which  is  insoluble  in  ammonium  sulphide. 
III.  IRIDIUM.  The  compounds  of  iridium  exist  chiefly 
in  three  conditions  of  oxidation,  of  which  the  di-,  tri-,  and 
tetrachlorides  may  serve  as  types,  (IrCl2;  Ir2Cl6;  IrCl4). 
The  iridium  compounds  are  reduced  to  the  metal  when 
mixed  with  sodium  carbonate  and  heated  in  the  outer 
flame  of  a  Bunsen  burner.  The  alkali  double  chlorides 
with  iridous  chloride,  (IrCl2),  are  in  general  soluble  in  water. 
Solutions  of  iridium  salts  in  the  lowest  condition  of  oxida- 
tion give  with  potassium  hydroxide  a  greenish  precipitate, 
which  tends  to  darken  when  boiled.  Reducing  agents, 
as  sodium  formate,  precipitate  metallic  iridium,  and  hydro- 
gen sulphide  precipitates  from  the  warmed  solution  a  brown 
iridium  sulphide  (IrS).  By  means  of  oxidizing  agents, 
solutions  of  iridous  salts  may  be  converted  into  the  high- 
est condition  of  oxidation.  From  solutions  of  this  latter 
type  potassium  hydroxide  throws  down  a  dark-brown  pre- 
cipitate of  potassium -iridium  chloride,  (IrCl4'2KCl),  and 
hydrogen  sulphide  precipitates  slowly  a  brown  sulphide, 
(Ir2S3).  The  greater  number  of  iridium  compounds  are 
easily  reduced  by  hydrogen  on  being  heated.  The  pres- 


THE  PLATINUM  METALS.  137 

ence  of  indium  may  be  detected  by  the  blue  color  de- 
veloped when  the  compound  is  heated  with  concentrated 
sulphuric  acid  to  which  ammonium  nitrate  has  been  added. 

IV.  RHODIUM.     Although  three  oxides  of  rhodium  are 
known  and  described,  (RhO;  Rh203;  RhO2),  salts  of  only 
two  conditions  of  oxidation  are  generally  found;  of  these 
the  di-  and  trichlorides  are  types,  (RhCl2;  Rh2Cl6).     From 
solutions  of  rhodium  salts  reducing  agents  precipitate  the 
metal.     Hydrogen  sulphide  throws  down  from  a  cold  solu- 
tion the   sulphide   (Rh2S3),  and  from  a  hot  solution  the 
sulphydrate   (Rh2(SH)6).     The  insolubility  of  the   double 
chloride  of  rhodium  and  sodium,  (Rh2Cl'6NaCl),  in  water, 
and   of   the   double   nitrate   of   rhodium   and   potassium, 
(K6Rh6(NO2)12),  in  alcohol  is  made  use  of  in  separating  the 
metal  from  the  other  members  of  the  group.     Rhodium 
is  detected  in  the  presence  of  the  other  platinum  metals  by 
the  yellow  solution  obtained  after  fusion  with  potassium 
acid  sulphate  and  the  change  of  color  to  red  upon  the  ap- 
plication of  hydrochloric  acid. 

V.  RUTHENIUM.     In  the  variety  of  conditions  of  oxida- 
tion in  which  they  are  found,  the  compounds  of  ruthenium 
resemble  those  of  osmium.     The  lowest  three  oxides  are 
basic  in  character,  (RuO;  Ru2O3;  RuO2),  and  form  salts  of 
which  the  three  chlorides,  (RuCl2 ;  Ru2Cl6 ;  RuCl4),are  typical. 

The  trioxide,  (RuO3),  is  known  only  in  combination,  where 

i 
it  acts  as  an  acid  and  forms  salts  of  the  type  R2RuO4. 

Another  oxide,  (Ru2O7),  known  only  in  combination,  forms 

i 

salts  represented  by  the  formula  RRuO4.  The  tetroxide 
(RuO4)  is  volatile  and  similar  to  the  corresponding  oxide  of 
osmium  in  its  chemical  behavior;  it  has  a  characteristic 
odor.  A  solution  of  the  trichloride,  (Ru2Cl6),  throws  out, 
when  heated,  a  dark  precipitate  which  is  generally  sup- 
posed to  be  an  oxychloride;  this  precipitate  is  held  in 
suspension  in  the  liquid  and  gives  a  pronounced  coloration, 


I38  THE  RARER  ELEMENTS. 

even  in  very  dilute  solutions.  Hydrogen  sulphide,  acting 
upon  solutions  of  ruthenium  salts,  precipitates  a  mixture 
of  sulphides,  oxysulphides,  and  sulphur;  this  mixture  is 
brown  or  black,  and  may  contain  one  or  more  of  the  sul- 
phides Ru2S3,  RuS2,  and  RuS3. 

Estimation.  The  platinum  metals  are  weighed  in  the 
elementary  condition,  obtained  as  described  under  Prepara- 
tion of  the  various  metals. 

Osmium  may  be  determined  volumetrically  by  causing 
potassium  iodide  to  act  upon  the  tetroxide  in  the  presence 
of  dilute  sulphuric  acid,  (OsO4  +  4KI  +  2H2SO4  =  OsO2  + 
2K2SO4  +  4l  +  2H2O),  and  estimating  by  means  of  sodium 
thiosulphate  the  iodine  thus  liberated  (Klobbie,,  Chem. 
Central-Blatt  (1898)  n,  65  (abstract)., 

Separation.  The  separation  of  the  platinum  metals 
has  been  considered  under  Platinum.  The  following  are 
additional  references:  Gibbs,  Amer,  Jour.  Sci.  [2]  xxxi,  63; 
xxxiv,  341;  xxxvn,  57;  Forster,  Zeitsch.  anal.  Chem. 
v,  117;  Bunsen,  Liebig  Annal.  CXLVI,  265;  Chem.  News 
xxi,  39;  Deville  and  Debray,  Compt.  rend.  LXXXVII,  441; 
Chem.  News  xxxvin,  188;  Wilm,  Ber.  Dtsch.  chem.  Ges. 
xvi,  1524;  Leidie,  Compt.  rend,  cxxxi,  888;  Bull.  Soc. 
Chim.  d.  Paris  [3]  xxvn,  179. 

EXPERIMENTAL  WORK   ON   THE    PLATINUM 
METALS.* 

Experiment  135.  Precipitation  of  palladious  iodide, 
(PdI2).  To  a  solution  of  a  palladium  salt  add  a  little 
potassium  iodide  in  solution. 

Experiment  136.  Precipitation  of  palladious  sulphide i, 
(PdS).  (a)  Pass  hydrogen  sulphide  through  a  solution  of 
a  palladious  salt. 

*  For  experimental  work  on  platinum  see  page  129. 


EXPERIMENTAL   WORK  ON   THE  PLATINUM  METALS.       139 

(b)  Try  the  action  of  ammonium  sulphide  upon  a  palla- 
dious  salt  in  solution. 

Experiment  137.  Precipitation  of  elementary  palladium. 
To  a  solution  of  a  palladium  salt  add  sodium  carbonate 
to  alkaline  reaction;  add  also  a  few  drops  of  alcohol  and 
boil. 

Experiment  138.  Action  of  nitric  acid  upon  palladium. 
Try  the  action  of  nitric  acid  upon  a  small  piece  of  metallic 
palladium. 

Experiment  139.  Precipitation  of  osmium  sulphide, 
(OsS4).  (a)  To  a  solution  of  osmium  tetroxide  acidified 
with  hydrochloric  acid  add  a  little  hydrogen  sulphide. 

(b)  Try  the  action  of  ammonium  sulphide  upon  the 
tetroxide  in  solution. 

Experiment  140.  Formation  of  potassium  osmate, 
(K2OsO4).  To  a  solution  of  osmium  tetroxide  add  a  solu- 
tion of  potassium  hydroxide.  Note  the  yellow  color. 

Experiment  141.  Action  of  reducing  agents  upon  osmium 
tetroxide.  Try  the  action  of  an  alkali  sulphite,  formic  acid, 
and  tannic  acid,  respectively,  upon  a  solution  of  osmium 
tetroxide. 

Experiment  142.  Action  of  osmium  tetroxide  upon  hy- 
driodic  acid.  To  a  solution  of  osmium  tetroxide  add  a  little 
starch  paste  and  a  small  crystal  of  potassium  iodide.  Acid- 
ify the  solution  with  dilute  sulphuric  acid.  Note  the  blue 
color,  due  to  free  iodine. 

Experiment  143.  Precipitation  of  elementary  osmium. 
(a)  To  a  solution  of  the  tetroxide  add  stannous  chloride. 

(b)  Try  the  action  of  zinc  and  hydrochloric  acid  upon 
a  solution  of  the  tetroxide. 

Experiment  144.  Odor  test  for  osmium.  Warm  a  dilute 
solution  of  osmium  tetroxide,  or  warm  with  nitric  acid  a 
solution  of  any  osmium  salt  of  the  lower  condition  of 
oxidation.  Note  the  odor. 

Experiment     145.    Precipitation    of    iridium     sulphide, 


14°  THE  RARER  ELEMENTS. 

(Ir2S3).  Pass  hydrogen  sulphide  through  a  solution  of 
iridium  tetrachloride.  Try  the  action  of  ammonium  sul- 
phide upon  the  precipitate. 

Experiment  146.  Formation  of  the  double  chlorides  of 
iridium  with  ammonium  and  potassium,  ((NH4)2IrCl6  and 
K2IrCl6).  To  separate  portions  of  a  fairly  concentrated 
solution  of  iridium  tetrachloride  add  ammonium  chloride 
and  potassium  chloride  respectively. 

Experiment  147.  Reduction  of  iridium  salts,  (a)  To  a 
solution  of  iridium  tetrachloride  add  oxalic  acid. 

(b)  Try  similarly  the  action  of  zinc  upon  an  acid  solu- 
tion of  the  salt. 

Experiment  148.  Action  of  sodium  hydroxide  upon 
iridium  tetrachloride.  Add  sodium  hydroxide  in  excess 
to  iridium  tetrachloride  and  warm.  Note  the  change  in 
color.  The  iridium  salt  is  said  to  be  reduced  to  the  tri- 
chloride by  this  treatment.  Acidify  with  hydrochloric 
acid  and  add  potassium  chloride.  Note  the  absence  of 
precipitation. 

Experiment  149.  Precipitation  of  rhodium  sulphide, 
(Rh2Ss).  Pass  hydrogen  sulphide  through  a  solution  of 
sodium-rhodium  chloride.  Try  the  action  of  ammonium 
sulphide  upon  the  sulphide  precipitated. 

Experiment  150.  Reduction  of  rhodium  salts.  To  an 
acid  solution  of  a  rhodium  salt  add  zinc. 

Experiment  151.  Formation  of  the  double  nitrite  of  potas- 
sium and  rhodium,  (K3Rh(NO2)6).  To  a  solution  of  sodium- 
rhodium  chloride  add  potassium  nitrite  in  solution  and 
warm.  Try  the  action  of  hydrochloric  acid  upon  the 
precipitate. 

Experiment  152.  Precipitation  of  rhodium  hydroxide, 
(Rh(OH)3).  Note  the  first  action  and  the  action  in  excess 
of  sodium  or  potassium  hydroxide  upon  a  solution  of  sodium- 
rhodium  chloride.  Boil  the  solution  just  obtained. 

Experiment    153.     Precipitation   of  ruthenium  sulphide, 


GOLD.  141 

(Ru2S3).  (a)  To  a  solution  of  ruthenium  trichloride  add 
hydrogen  sulphide. 

(b)   Use  ammonium  sulphide  as  the  precipitant. 

Experiment  154.  Formation  of  the  soluble  double  nitrite 
of  ruthenium  and  potassium,  (K3Ru(N02)6).  To  a  solution 
of  ruthenium  trichloride  add  a  solution  of  potassium  nitrite. 
Note  the  color.  Add  ammonium  sulphide  to  the  solution. 

Experiment  155.  Precipitation -of  ruthenium  hydroxide,. 
(Ru(OH)3).  To  a  solution  of  ruthenium  trichloride  add 
sodium  or  potassium  hydroxide  in  solution. 

Experiment  156.  Precipitation  of  metallic  ruthenium. 
To  an  acid  solution  of  a  ruthenium  salt  add  metallic  zinc. 

GOLD,  Au,  197.2. 

Discovery.  Gold  is  probably  one  of  the  earliest  known 
of  the  metals.  In  very  ancient  records  frequent  mention 
is  made  of  its  uses.  As  far  back  as  3600  B.C.  in  the  Egyp- 
tian code  of  Menes  a  ratio  of  value  between  gold  and  silver 
(2.5:1)  is  mentioned.  Rock  carvings  of  Upper  Egypt 
dating  from  2500  B.C.  show  crude  representations  of  the 
washing  of  gold-bearing  sands  in  stone  basins,  and  of  the 
melting  of  the  metal  in  simple  furnaces  by  means  of  mouth 
blowpipes.  In  fact  the  discovery  of  gold  dates  back  to 
the  beginnings  of  civilization.  The  search  for  it  furnished 
the  motive  of  many  voyages  of  discovery  and  conquest, 
which  resulted  in  the  extension  of  civilization;  and  from 
the  desire  to  change  the  base  metals  into  gold  sprang  the 
study  of  alchemy,  from  which  developed  the  science  of 
chemistry. 

Occurrence.  Gold  occurs  in  nature  both  free  and  in 
combination.  Free  or  native  gold  is  found  (i)  as  vein 
gold,  in  the  quartz  veins  which  intersect  metamorphic 
rocks,  and  (2)  as  placer  gold,  generally  in  the  form  of  grains 
or  nuggets,  in  alluvial  deposits  of  streams.  Native  gold  is. 


X42  THE  RARER  ELEMENTS. 

usually  alloyed  with  'silver,  which  sometimes  amounts  to  as 
much  as  fifteen  per  cent,  of  the  alloy.  Iron  and  copper 
are  sometimes  present,  and  bismuth,  palladium,  and  rho- 
dium alloys  are  known. 

In  combination  gold  is  found  as  follows: 

Petzite,  (AgAu)2Te,  contains  ......  18-24%  Au 

Sylvanite,  (AuAg)Te2,  "  ......  26-29%  " 

Goldschmidtite,  Au2AgTe6,  "  ......  31-32%  " 

Krennerite,  (Au,Ag)Te2-AuTe2,  "  ......  30-34%  " 

Calaverite,  (Au,Ag  Te2-AuTe2,  «  ......  38-42%  " 

Kalgoorlite,  HgAu2Ag6Te6,  "  ......  20-21%  " 

Nagyagite,  Au2PbuSb3Te7S17,  "  ...... 


Extraction.  The  six  processes  indicated  below  follow 
the  principal  methods  that  have  been  employed  for  the 
extraction  of  gold. 

(1)  Washing  or  Hydraulicking.     This  method  is  applied 
mainly    to    placer    deposits.     Powerful    jets    of  water  are 
directed   upon  the  gold-bearing  sands,    causing   them   to 
pass  through  a  series  of  sluices.     Because  of  its  higher 
specific  gravity  the  gold  is  largely  left  behind,  while  the 
other  materials  are  carried  away. 

(2)  Amalgamation    (primitive}.     In     this     process    the 
crushed  ore  or  the  gold-bearing  sand  is  first  washed,  to 
remove  the  greater  part  of  the  light,  worthless  material, 
and  the  remainder  is  rubbed  with  mercury  in  a  mortar. 
The   amalgam   thus   obtained   is   heated,    whereupon   the 
mercury  is  volatilized  and  the  gold  remains. 

(3)  Stamp  battery  amalgamation.     The  ore  is  pulverized 
and  mixed  with  water,  and  in  the  form  of  pulp  caused  to 
pass  over  a  series  of*  amalgamated  copper  plates.     Gold 
amalgam  forms  on  the  plates,  and  from  time  to  time  it  is 
removed  and  cupelled. 

(4)  Chlorination.     (a)  Vat    process.     The   crushed   ore 
is  placed  loosely  in  large  vats  and  moistened  with  water. 


GOLD.  143 

Chlorine  is  forced  in,  and  the  whole  is  allowed  to  stand  for 
about  twenty  -four  hours.  The  material  is  then  leached 
with  water  until  the  washings  give  no  further  test  for  gold. 
The  solution  of  gold  chloride  thus  obtained  is  treated  with 
sulphur  dioxide,  to  destroy  the  excess  of  chlorine,  and  then 
with  hydrogen  sulphide.  The  gold  sulphide  thus  precipi- 
tated is  decomposed  with  borax  and  the  gold  is  melted 
into  bullion. 

(b)  Barrel  process.  Into  large  barrels  are  put  water 
and  sulphuric  acid,  the  ore,  and  chloride  of  lime.  The 
barrels  are  then  closed  and  rotated  for  a  period  varying  from 
one  hour  to  four  hours.  At  the  end  of  that  time  the  con- 
tents are  leached  and  the  gold  is  extracted  as  described 
above. 

The  chlorination  process  is  generally  applied  to  low- 
grade  ores,  and  these  must  have  been  roasted  unless  the 
gold  occurs  in  them  native. 

(5)  Cyanide  process.  The  ore,  ground  fine,  is  placed 
in  large  vats,  and  a  dilute  solution  (.2-.  5%)  of  potassium 
cyanide  is  forced  in.  After  a  time  the  solution  is  drawn  off 
and  passed  over  zinc  shavings,  upon  which  the  gold  is  de- 
posited as  a  black  slime.  The  mixture  of  zinc  and  gold 
is  either  treated  with  sulphuric  acid,  to  dissolve  the  zinc,  or 
roasted  with  a  flux  of  niter  and  carbonate  of  soda.  The 
reactions  which  take  place  in  the  cyanide  process  may  be 
represented  as  follows: 


(1)  4Au+8KCN  +  O2  +  2H2O=4KAu(CN)2H-4KOH. 

(2)  2KAu(CN)2  +  2Zn  +  2H2O  = 

2KOH  +  H2  +  2Zn(CN)2 

(6)  Smelting.  In  smelting  the  gold  ore  is  mixed  with 
some  other  metallic  ore  appropriately  chosen,  and  the 
mixture  is  subjected  to  intense  heat.  The  gold  alloys 
with  the  other  metal,  and  the  alloy  is  separated  from  the 
residue,  or  slag,  and  worked  for  gold.  Three  modifications 


144  THE  RARER  ELEMENTS. 

of  this  important  process  are  in  common  use,  viz.,  lead, 
copper  matte,  and  iron  matte  smelting.  The  process  of 
lead-smelting  is  in  outline  as  follows:  The  alloy  obtained 
by  heating  a  mixture  of  gold  and  lead  ores  is  melted  with 
zinc.  The  gold  and  silver  combine  with  the  zinc  and  rise 
to  the  surface,  leaving  the  lead  below.  The  alloy  of  gold, 
silver,  and  zinc  is  then  skimmed  off  and  roasted.  The  zinc 
passes  off,  leaving  the  gold  and  silver,  which  are  separated 
by  electrolysis. 

The  Element.  A.  Preparation.  As  extracted  from  its 
ores  gold  is  in  the  elementary  condition  (vid.  Extraction). 

B.  Properties.  Of  a  characteristic  yellow  color,  gold 
is  the  most  malleable  and  ductile  of  the  metals.  It  is  about 
as  soft  as  silver.  It  is  insoluble  in  acids,  but  is  attacked  by 
aqua  regia,  chlorine,  bromine,  and  potassium  cyanide.  Its 
melting-point  is  1037°  C., — just  above  that  of  copper.  Gold 
alloys  with  nearly  all  the  metals.  It  is  occasionally  found 
crystallized  in  the  cubic  system.  It  is  a  good  conductor 
of  heat  and  electricity.  Its  specific  gravity  is  19.49. 

Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  gold  may  be  considered  typical  forms: 

Oxides Au2O  Au2O2  Au2O3 

Hydroxide Au(OH)3 

Chlorides AuCl  Au2Cl4  AuCl3 

Double     chlorides,  x 

many  of  the  types  AuCl3  •  RC1 

AuCl3-RCl3 

Bromides AuBr  Au2Br4  AuBr3 

Double    bromides,  T 

of  the  type AuBr3  •  RBr 

Iodides Aul  AuI3 

Double  iodides,  of  T 

the  type AuI3-RI 

Sulphides Au2S  Au2S2  Au2S3 

2Au2S3-5Ag2S 
Double  sulphides . .  Au2S  •  Na2S  2 Au2S3  •  sMo^ 

Au2S3-3Mo$4 


GOLD.  145 

Sulphites  (double)  Au2SO3 •  3Na2SO3+  3H2O  Au2(SO3)3  •  sK2SO3+  5H2O 

Sulphates AuSO4  Au2(SO4)3-  K2SO4 

Nitrate Au(NO3)3-HNOj, 

Cyanides AuCN  Au(CN)3 

Double  cyanides.  .  AuCN  •  KCN  Au(  CN)  3  •  KCN,  etc. 

Sulphocyanides.  .  .  AuCNS •  KCNS  Au(CNS)3 •  KCNS 

B.  Characteristics.  The  compounds  of  gold  are  known 
chiefly  in  two  conditions  of  oxidation,  of  which  attrous 
oxide,  (Au2O),  and  auric  oxide,  (Au2O3),  serve  as  types. 
When  metallic  gold  is  dissolved  in  aqua  regia  auric 
chloride  is  formed,  a  yellow  crystalline  salt  soluble  in 
water;  when  auric  chloride  is  heated  to  180°  C.  it  goes 
over  to  aurous  chloride,  a  white  powder  insoluble  in 
water.  The  aurous  salts  resemble  the  salts  of  silver 
and  of  copper  in  the  cuprous  condition;  the  auric  salts 
resemble  those  of  aluminum  and  of  iron  in  the  ferric 
condition.  The  auric  hydroxide,  (Au(OH)3),  is  acidic 

in  character  and  unites  with  bases  to  form  aurates  of  the 

i 

type  RAuO2.  Hydrogen  sulphide  precipitates  brownish- 
black  auric  sulphide,  (Au2S3  or  Au2S2  +  S),  from  cold  solu- 
tions of  gold  salts,  and  steel-gray  aurous  sulphide,  (Au2S  or 
Au2S  +  S),  from  hot  solutions.  Salts  of  gold  in  solution 
are  easily  reduced  to  the  metal  by  reducing  agents. 

Estimation.  A.  Gravimetric.  Gold  is  weighed  as  the 
metal.  From  solutions  it  is  precipitated  by  reducing  agents, 
such  as  ferrous  sulphate,  oxalic  acid,  formaldehyde,  and 
hydrogen  dioxide  in  alkaline  solution. 

B.  Volumetric.  Gold  may  be  determined  volumetrically 
(i)  by  allowing  potassium  iodide  to  act  upon  auric  chloride, 
(AuCl3  +  3KI=3KCl  +  AuI  +  I2),  and  estimating  the  iodine 
thus  freed  by  means  of  thiosulphate  (Peterson,  Zeitsch. 
anorg.  Chem.  xix,  63;  Gooch  and  Morley,  Amer.  Jour. 
Sci.  [4]  vni,  261;  Maxson,  Amer.  Jour.  Sci.  [4]  xvi);  (2) 
by  warming  a  solution  of  auric  chloride  with  a  measured 
amount  of  arsenious  acid  solution  which  must  be  in  ex- 


146  THE  RARER  ELEMENTS. 

cess,  (3As2O3  +  4AuCl3  +  6H2O  =  3As2O5  +  1 2HC1  +  4Au),  and 
determining  the  excess  of  arsenious  acid  by  iodine  in 
the  usual  way  (Rupp,  Ber.  Dtsch.  chem.  Ges.  xxxv,  2011; 
Maxson,  loc.  cit.). 

Separation.  Gold  and  platinum  fall  into  the  analyt- 
ical group  of  arsenic,  antimony,  and  tin.  From  these 
they  may  be  separated  by  the  following  process:  fusion 
of  the  sulphides  with  sodium  carbonate  and  niter,  and 
removal  of  the  arsenic  by  extraction  with  water ;  treatment 
of  the  insoluble  residue  with  zinc  and  hydrochloric  acid, 
which  reduces  the  tin  and  antimony  to  the  metallic  con- 
dition; boiling  with  hydrochloric  acid,  which  dissolves  the 
tin;  then  with  nitric  and  tartaric  acids,  which  dissolves 
the  antimony,  leaving  gold  and  platinum. 

For  the  separation  of  gold  from  platinum  and  the  plat- 
inum metals  vid.  Platinum. 

EXPERIMENTAL  WORK  ON  GOLD. 

Experiment  157.  Extraction  of  gold  from  its  ores,  (a) 
Digest  for  several  hours  in  a  beaker  on  a  steam-bath  about 
100  grm.  of  finely  ground  gold  ore  with  a  dilute  solution  of 
potassium  cyanide,  adding  water  from  time  to  time  to  re- 
place the  liquid  evaporated.  Filter,  pass  the  filtrate  several 
times  through  a  funnel  containing  zinc  shavings,  until  upon 
testing  the  liquid  with  a  fresh  piece  of  zinc  no  discoloration 
of  the  metal  is  observed.  Dissolve  the  zinc  in  hydrochloric 
acid  to  remove  the  black  deposit.  Filter,  dissolve  the  resi- 
due in  aqua  regia,  remove  the  excess  of  acid  by  evaporation, 
and  test  for  gold  by  stannous  chloride,  ferrous  sulphate,  etc. 

(b)  Mix  in  a  glass-stoppered  bottle  about  100  grm.  of 
finely  ground  ' '  oxidized ' '  or  previously  roasted  ore  with  a 
little  bleaching  salt  and  enough  water  to  give  the  mass  the 
consistency  of  thin  paste.  Then  add  gradually  enough 
sulphuric  acid  to  start  an  evolution  of  chlorine.  Close  the 


EXPERIMENTAL   WORK  ON   GOLD.  147 

bottle  and  shake  it,  to  insure  a  thorough  mixing  of  the 
contents.  Allow  the  action  to  go  on  for  several  hours,  agitat- 
ing the  mass  occasionally,  and  taking  care  to  have  an  excess 
of  chlorine  present  throughout  the  process.  Extract  with 
water,  concentrate  if  necessary,  and  test  for  gold  in  the 
solution.  A  two  per  cent,  solution  of  bromine  may  be 
substituted  for  the  materials  generating  chlorine. 

Experiment  158.  Precipitation  of  the  sulphide  of  gold, 
(Au2S3  or  Au2S2  +  S  ?) .  Into  a  cold  solution  of  auric  chloride 
pass  hydrogen  sulphide.  Try  the  action  of  yellow  am- 
monium sulphide  upon  the  precipitate. 

Experiment  159.  Formation  of  aurous  iodide,  (AuT). 
To  a  solution  of  auric  chloride  add  a  few  drops  of  a  dilute 
solution  of  potassium  iodide.  Note  the  precipitate,  and 
the  solvent  action  of  an  excess  of  the  reagent. 

Experiment  160.  Formation  of  ammonia  aurate,  "ful- 
minating gold"  ((NH3)2Au2O3).  To  a  very  dilute  solution 
of  a  salt  of  gold  add  a  little  ammonium  hydroxide. 

CAUTION.  Do  not  attempt  to  isolate  the  precipitate. 
Note  that  neither  potassium  nor  sodium  hydroxide  gives 
a  precipitate  under  similar  conditions  of  dilution. 

Experiment  161.  Formation  of  the  "purple  of  Cassius" 
To  a  very  dilute  solution  of  a  gold  salt  add  a  drop  or  two 
of  dilute  stannous  chloride  solution. 

Experiment  162.  Precipitation  of  gold.  To  separate 
portions  of  a  solution  of  a  gold  salt  add  ferrous  sulphate 
and  oxalic  acid  in  solution.  Observe  the  color  by  trans- 
mitted light. 

Experiment  163.  Solvent  action  of  certain  reagents  upon 
gold.  Try  separately  upon  metallic  gold  the  action  of 
aqua  regia,  chlorine  or  bromine  water,  and  a  dilute  solution 
of  potassium  cyanide. 


148  THE  RARER  ELEMENTS. 


THE  NEWLY    DISCOVERED  GASES  OF  THE 
ATMOSPHERE. 

Argon,  A,  39.9  Krypton,  Kr,  81.8 

Helium,  He,  4  Neon,  Ne,  20 

Xenon,  X,   128 

Discovery.  In  1892  Lord  Rayleigh,  while  engaged  in 
the  study  of  the  density  of  elementary  gases,  made  the  im- 
portant observation  that  the  nitrogen  obtained  from  nitric 
acid  or  ammonia  was  about  one  half  of  one  per  cent,  lighter 
than  atmospheric  nitrogen  (Proc.  Royal  Soc.  LV,  340). 
An  investigation  of  this  difference  led  to  the  discovery 
two  years  later  of  the  gas  Argon  (dpyos,  inert)  by  Lord 
Rayleigh  and  Professor  William  Ramsay  (Proc.  Royal 
Soc.  LVII,  265;  Amer.  Chem.  Jour,  xvn,  225).  An  experi- 
ment made  by  Cavendish  in  1785  seems  also  to  have  resulted 
in  the  separation  of  this  gas  (Phil.  Trans.  Roy.  Soc.  (1785) 
LXXV,  372,  and  (1788)  LXXVIII,  271). 

In  the  course  of  analytical  work  on  uraninite  undertaken 
by  Hillebrand  in  1888,  a  gas  which  he  thought  to  be  nitro- 
gen was  obtained  upon  the  boiling  of  the  mineral  with  dilute 
sulphuric  acid  (Bull.  U.  S.  Geol.  Sur.  No.  78,  p.  43 ;  Amer. 
Jour.  Sci.  [3]  XL,  384).  In  1895  Ramsay,  whose  attention 
had  been  called  to  Hillebrand 's  work,  and  who  doubted 
whether  nitrogen  could  be  obtained  by  the  method  de- 
scribed, prepared  some  of  the  gas  by  Hillebrand 's  process 
from  cleveite,  a  variety  of  uraninite.  He  then  sparked  the 
gas  with  oxygen  over  soda  to  remove  the  nitrogen.  Ob- 
serving very  little  contraction,  he  removed  the  excess  of 
oxygen  by  absorption  with  potassium  pyrogallate  and 
examined  the  residual  gas  spectroscopically.  The  spec- 
trum showed  argon  and  hydrogen  lines,  and  in  addition  a 
brilliant  yellow  line,  (D3),  coincident  with  the  helium  line 


THE  NEWLY  DISCOVERED  GASES  OF  THE  ATMOSPHERE.     149 

of  the  solar  chromosphere  discovered  by  Lockyer  in  1868 
(Proc.  Royal  Soc.  LVIII,  65,  81).  The  only  previous  note 
regarding  helium  as  a  terrestrial  element  is  a  statement 
by  Palmieri,  in  1881,  that  a  substance  ejected  from  Vesu- 
vius showed  the  line  D3  (Rend.  Ace.  di  Napoli  xx,  233) ; 
he  failed  to  describe  his  treatment  of  the  material,  how- 
ever, and  he  seems  to  have  made  no  further  investigation  of 
the  subject.  Kayser  first  detected  helium  in  the  atmos- 
phere, in  1895  (Chem.  News  LXXII,  89),  several  months 
after  Ramsay's  discovery. 

The  year  1898  witnessed  the  discovery  by  Ramsay  and 
Travers  of  three  other  inert  atmospheric  gases.  Having 
.allowed  all  but  one  seventy -fifth  of  a  given  amount  of 
liquid  air  to  evaporate,  and  having  removed  the  oxygen 
and  nitrogen  remaining  by  sparking  over  soda,  they  ob- 
tained a  small  amount  of  a  gas  which,  while  showing  a  feeble 
spectrum  of  argon,  gave  new  lines  as  well.  This  newly 
discovered  gas  they  named  Krypton,  from  Kpvnros,  hid- 
den (Proc.  Royal  Soc.  LXIII,  405). 

By  fractioning  the  residue  after  the  evaporation  of  a 
large  amount  of  liquid  air  they  found  evidence  of  a  gas  of 
greater  density  than  krypton,  and  for  this  heavy  gaseous 
•element  the  name  Xenon  (Zeros,  stranger)  was  chosen 
(Chem.  News  LXXVIII,  154). 

The  third  discovery  of  the  year  by  the  same  investigators 
was  that  of  Neon  (reo?,  new),  a  gas  of  less  density  than 
.argon.  The  first  fraction  obtained  from  the  evaporation 
of  liquid  air  was  mixed  with  oxygen  and  sparked  over 
soda,  and  the  excess  of  oxygen  was  removed  by  phosphorus. 
The  remaining  gas  yielded  a  new  and  characteristic  spectrum 
(Proc.  Royal  Soc.  LXIII,  437). 

Occurrence.  Argon  forms  about  one  per  cent,  of  the  air 
by  volume.  It  is  found  in  small  quantities  in  gases  from 
certain  mineral  springs,  e.g.  Bath,  Cauterets,  Wildbad, 
Voslau,  the  sulphur  spring  of  Harrogate;  also  in  the  gases 


15°  THE  RARER  ELEMENTS. 

occluded  in  rock  salt.  It  has  been  detected  in  some  helium- 
bearing  minerals,  e.g.  cleveite,  broggerite,  uraninite,  and 
malacon. 

Helium,  the  existence  of  which  was  first  observed  in 
the  sun,  occurs  in  very  small  proportion  in  the  terrestrial 
atmosphere.  The  chief  sources  of  the  gas  have  been  certain 
rare  minerals,  among  which  are  uraninite  (pitch -blende) , 
cleveite,  monazite,  fergusonite,  samarskite,  columbite,  and 
malacon.  It  has  been  found  also  in  some  mineral  springs r 
e.g.  Bath,  Cauterets,  and  Adano,  near  Padua. 

The  other  gases  of  this  group  are  present  in  the  air  in 
very  minute  quantities.  Neon  is  said  to  constitute  0.002  5  % 
and  krypton  0.00002%  of  the  atmosphere.  Traces  of  neon 
have  been  detected  in  the  helium  from  the  springs  of  Bath. 

Extraction.  Argon,  contaminated  with  a  greater  or  less 
percentage  of  the  associated  gases,  may  be  extracted  by  the 
following  methods : 

(1)  From  atmospheric  nitrogen.     The  nitrogen  is  passed 
over  red-hot  magnesium  filings;  a  nitride  is  thus  formed, 
while  the  argon  is  left  uncombined  (Ramsay).      Heated 
lithium  may  be  substituted  for  magnesium. 

(2)  From  air.     Induction  sparks  are  passed  through  a 
mixture  of  oxygen  and  air  contained  in  a  vessel  which  is 
inverted  over  caustic  potash.     The  oxygen   and  nitrogen 
combine  and  dissolve  in  the  potassium  hydroxide,  leaving 
the  argon  (Rayleigh). 

Helium  may  be  obtained  from  its  mineral  sources  by 
boiling  the  material  with  dilute  sulphuric  acid,  or  by  heat- 
ing in  vacuo. 

Krypton  and  xenon  are  extracted  as  follows:  After 
the  evaporation  of  a  large  amount  of  liquid  air  the  residue 
is  freed  from  oxygen  and  nitrogen  and  liquefied  by  the 
immersion  of  the  containing  Vessel  in  liquid  air.  The 
greater  part  of  the  argon  can  be  removed  as  soon  as  the 
temperature  rises.  By  repetitions  of  this  process  the 


THE  NEWLY  DISCOVERED  GASES  OF  THE  ATMOSPHERE.     I5L 

three  gases  can  be  separated  from  one  another,  krypton 
exercising  much  greater  vapor  pressure  than  xenon  at  the 
temperature  of  boiling  air  (Ramsay  and  Travers,  Proc. 
Royal  Soc.  LXVII,  330). 

Neon  is  obtained  from  the  gas,  largely  nitrogen,  that 
first  evaporates  from  liquid  air.  This  gas  is  liquefied,  and 
a  current  of  air  is  blown  through  it.  The  material  that 
first  evaporates  is  passed  over  red-hot  copper,  to  remove 
the  oxygen,  and  after  being  freed  from  nitrogen  in  the 
usual  manner,  is  liquefied.  By  fractional  distillation  helium 
and  neon  are  removed,  and  argon  is  left  behind.  By  the 
use  of  liquefied  hydrogen  helium  and  neon  are  separated, 
as  neon  is  liquefied  or  solidified  at  the  temperature  of  boil- 
ing hydrogen,  while  helium  remains  gaseous.  Several 
fractionations  are  necessary  to  obtain  pure  neon  (Ramsay 
and  Travers,  Proc.  Royal  Soc.  LXVII,  330). 

Properties.  The  newly  discovered  constituents  of  the 
atmosphere  are  inert,  colorless,  probably  monatomic  gases, 
which  have  not  been  known  to  form  definite  compounds. 

Argon  is  somewhat  soluble  *  in  water.  Its  density  is 
19.96  and  its  specific  heat  1.645.  It  solidifies  at  —  191°  C., 
melts  at  —  189.5 °C.,  and  boils  at  —  185°  C.  Argon  gives 
two  distinct  spectra,  according  to  the  strength  of  the  in- 
duction current  employed  and  the  degree  of  exhaustion  in 
the  tube.  When  the  pressure  of  the  argon  is  3  mm.  the 
discharge  is  orange-red  and  the  spectrum  shows  two  par- 
ticularly prominent  red  lines.  If  the  pressure  is  further 
reduced,  and  a  Ley  den  jar  is  intercalated  in  the  circuit, 
the  discharge  becomes  steel-blue  and  the  spectrum  shows 
a  different  set  of  lines  (Crookes,  Amer.  Chem.  Jour,  xvn, 

251)- 

Helium  is  slightly  soluble  t  in  water.  Its  density  is 
i  .98.  Its  spectrum  is  characterized  by  five  brilliant  lines, — 

*  100  volumes  of  water  will  dissolve  3.7  volumes  of  argon  at  20°  C. 

f  100  volumes  of  water  will  dissolve  about  1.4  volumes  of  helium  at  20°  C. 


152  THE  RARER  ELEMENTS. 

one  each  in  the  red,  yellow,  blue-green,  blue,  and  violet. 
Reference  has  already  been  made  to  the  yellow  line  D3. 

Krypton  is  less  volatile  than  argon.  Its  density  is 
40.78.  Its  spectrum  is  characterized  by  a  bright  line  in  the 
yellow  and  one  in  the  green. 

Xenon  also  is  less  volatile  than  argon,  and  it  has  a 
much  higher  boiling-point.  Its  density  is  64.  Its  spectrum 
is  similar  in  character  to  that  of  argon,  though  the  position 
of  the  lines  is  different.  With  the  ordinary  discharge  the 
glow  in  the  tube  is  blue  and  the  spectrum  shows  three  red 
and  about  five  brilliant  blue  lines.  With  the  jar  and 
spark-gap  the  glow  changes  to  green  and  the  spectrum  is 
characterized  by  four  green  lines  (Ramsay  and  Travers, 
Chem.  News  LXXVIII,  155). 

Neon  is  more  volatile  than  argon.  Its  density  is  9.96. 
Its  spectrum  is  characterized  by  bright  lines  in  the  red, 
orange,  and  yellow,  and  faint  lines  in  the  blue  and  violet. 

RECENT   UNCONFIRMED   DISCOVERIES. 

In  September,  1896,  Barriere  announced  the  discovery 
in  monazite  sands  of  an  unknown  element  which  differed 
from  the  members  of  the  cerium  group  and  from  thorium 
and  zirconium  in  forming  no  double  sulphate  with  either 
sodium  or  potassium  sulphate,  and  from  the  members  of 
the  yttrium  group  in  being  precipitable  by  sodium  thio- 
sulphate.  He  gave  as  the  approximate  atomic  weight 
of  the  element  104,  and  proposed  for  it  the  name  Lucium 
(Chem.  News  LXXIV,  159).  A  few  weeks  later  Crookes 
examined  some  of  Barriere 's  material,  and  declared  lucium 
to  be  yttrium  with  some  admixture  of  erbium,  didymium, 
and  ytterbium  (Chem.  News  LXXIV,  259).  The  following 
year  Shapleigh  confirmed  Crookes 's  results,  and  pointed 
out  the  weak  places  in  Barriere 's  deductions  (Chem.  News 
LXXVI,  41). 


RECENT  UNCONFIRMED  DISCOVERIES.  153 

In  1897  Chruschtschoff  called  attention  to  a  new  member 
of  the  didymium  group  which  he  distinguished  from  praseo- 
and  neodymium  by  the  blue  color  of  its  salts.  The  spec- 
trum was  in  part  that  of  neodymium.  He  suggested  the 
name  Glaukodymium  (yhavxos,  blue-gray)  (Jour.  Rus. 
Phys.  Chem.  Soc.  xxix,  206).  Although  it  is  considered 
quite  possible  that  praseo-  and  neodymium  are  not  simple 
bodies,  no  confirmation  of  ChruschtschofI  's  discovery  has 
appeared. 

Nasini,  Anderlini,  and  Salvadori,  in  1898,  discovered 
in  the  spectra  of  gases  from  the  Solfatara  di  Pozzuoli  and 
the  fumaroles  of  Vesuvius  a  line  (1474  K)  of  the  corona 
never  before  observed  in  terrestrial  matter.  They  called 
the  unknown  gas  the  presence  of  which  was  thus  indicated 
Coronium  (Atti  R.  Accad.  dei  Lincei,  Roma  [5]  vn,  II,  73 ; 
Amer.  Chem.  Jour,  xx,  698). 

The  same  year  Brush,  while  studying  the  relation  of 
pressure  to  the  heat  conductivity  of  gases,  extracted  from 
glass  a  gaseous  substance  which  seemed  to  be  different 
from  all  known  gases.  He  concluded  that  its  heat  con- 
ductivity was  100  if  H  =  i ;  its  density,  also  referred  to  hy- 
drogen as  the  standard,  was  o.oooi,  and  its  molecular 
weight  0.0002.  He  suggested  that  it  might  be  the  ether 
of  the  physicist,  and  proposed  for  it  the  name  Etherion 
(Amer.  Chem.  Jour,  xx,  873;  Chem.  News  LXXVIII,  197). 
Crookes,  upon  examination  of  the  evidence  given  by  Brush, 
pronounced  the  gas  probably  water  vapor  (Chem.  News 
LXXVIII,  221). 

About  the  time  that  Ramsay  and  Travers  announced 
the  discovery  of  krypton  and  neon  in  1898,  they  first 
mentioned  Metargon  (Proc.  Royal  Soc.  LXIII,  437).  It 
was  obtained  in  the  liquefaction  of  large  quantities  of  argon, 
remaining  in  the  form  of  a  white  solid  after  the  liquid 
had  largely  boiled  away.  The  gas  obtained  from  this 
solid  had  a  density  close  to  that  of  argon;  its  spectrum 


154  THE  RARER  ELEMENTS. 

resembled  that  of  argon  and  also  that  of  carbon.  Two 
years  later  the  same  investigators  announced  that  this 
gas  was  merely  argon  mixed  with  some  compounds  of  car- 
bon (Proc.  Royal  Soc.  LXVII,  329). 

Crookes,  in  1899,  stated  that  as  the  result  of  a  long 
series  of  fractional  fusions,  crystallizations,  and  precipi- 
tations of  salts  obtained  from  yttrium  earth,  he  had  dis- 
covered an  element  which  he  had  named  Monium.  A  little 
later,  in  recognition  of  the  Queen 's  jubilee,  he  changed  the 
name  to  Victorium  (Proc.  Royal  Soc.  LXV,  237).  The 
new  element  was  described  by  him  as  having  a  pale-brown 
color,  as  being  less  basic  than  yttrium,  as  being  easily 
soluble  in  acids,  and  as  forming  with  potassium  sulphate 
a  double  sulphate  less  soluble  than  the  corresponding 
salt  of  yttrium,  and  more  soluble  than  the  corresponding 
salts  of  the  cerium  group.  Assuming  the  oxide  to  be 
Vc2O3,  he  calculated  the  atomic  weight  as  117. 

Previous  to  1898  the  presence  of  "radiant  matter" 
in  uranium  and  thorium  minerals,  particularly  in  pitch- 
blende, had  frequently  been  noticed,  and  investigations 
of  the  phenomenon  had  been  carried  on.  It  is  not  yet 
fully  determined  whether  the  actinism  is  due  to  the  pres- 
ence in  these  minerals  of  certain  elements  having  distinct 
radioactive  properties,  though  three  substances  possessing 
this  quality,  and  differing  in  other  characteristics,  have 
been  isolated  and  described  as  compounds  of  newly  dis- 
covered elements.  In  1898  P.  and  C.  Curie  announced 
the  discovery  in  pitch-blende  of  Polonium  (Polonia, 
Poland),  and  the  next  year,  together  with  Bemont,  of 
another  element,  Radium*  (Compt.  rend,  cxxvn,  175, 
1215).  Also  in  1899  Debierne  named  Actinium  as  a  third 
radioactive  element  (Compt.  rend,  cxxx,  906). 

*  Recent  work  on  this  interesting  substance  has  led  many  chemists  to 
assign  radium  a  place  among  the  elements.  See  Mme.  Curie,  Compt.  rend, 
cxxxv,  161;  Runge  and  Precht,  Annal.  der  Phys.  u.  Chem.  [4]  x,  655; 

Hammer,  Chem.  News  LXXXVII,  25. 


RECENT  UNCONFIRMED  DISCOVERIES.  155 

In  the  summer  of  1901  Baskerville  described  some 
work  on  pure  thorium  salts  which  had  suggested  to  him 
the  probable  existence  of  an  unknown  element  associated 
with  thorium.  He  found  it  possible,  by  fractioning  pure 
thorium  dioxide,  to  obtain  two  oxides  of  specific  gravity 
9  25  and  10.53  respectively.  Radioactivity  increased  with 
specific  gravity,  the  oxide  of  lower  specific  gravity  being 
practically  inactive.  A  determination  of  the  atomic  weight 
of  thorium  from  the  pure  tetrachloride  gave  223.25,  as 
against  232.5,  the  generally  accepted  value.  The  probable 
atomic  weight  of  the  new  element  was  given  as  between 
260  and  280,  and  the  name  proposed  for  it  was  Carolinium, 
because  the  thorium  salts  were  prepared  from  the  monazite 
sands  of  the  Carolinas  (Jour.  Amer.  Chem.  Soc.  xxm,  761). 


INDEX. 


PAGE 

Actinium 154 

Argon 148 

Beryllium 16 

Caesium. I 

Carolinium 155 

Cerium 3° 

Columbium 65 

Coronium 153 

Decipium. 27 

Didymium 36 

Dysprosium.. 27 

Erbium 27 

Erythronium 84 

Etherion 153 

Gadolinium 27 

Gallium 75 

Germanium 55 

Glaukodymium 153 

Glucinum 16 

Gold 141 

Helium 149 

Holmium 27 

Indium 72 

Indium 130 

Krypton 149 

Lanthanum 36 

Lithium n 

Lucium 152 

Menachite 58 

Metargon 153 

Molybdenum 91 

Monium 154 

Neodymium 36 


Neon 149 

Niobium 65 

Ochroite 30 

Osmium 130 

Palladium 130 

Philippium 27 

Platinum .• 122 

Pluranium 131 

Polinium 131 

Polonium 154 

Praseodymium 36 

Radium 154 

Rhodium 130 

Rubidium 5 

Ruthenium 130 

Samarium 27 

Scandium 27 

Selenium 1 14 

Tantalum 65 

Tellurium 107 

Terbium 27 

Thallium 78 

Thorium 44 

Thulium 27 

Titanium .' 58 

Tungsten 96 

Uranium 101 

Vanadium 84 

Victorium 154 

Xenon 149 

Ytterbium 27 

Yttrium 20 

Zirconium 50 

157 


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Principles  of  Animal  Nutrition 8vo,  4  oo 

Budd  and  Hansen's  American  Horticultural  Manual: 

Part  I. — Propagation,  Culture,  and  Improvement 12010,  i  50 

Part  II. — Systematic  Pomology i2mo,  i  50 

Downing's  Fruits  and  Fruit-trees  of  America 8vo,  5  oo- 

Elliott's  Engineering  for  Land  Drainage i2mo,  i  so- 
Practical  Farm  Drainage i2mo,  i  o 

Green's  Principles  of  American  Forestry.     (Shortly.) 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll.) i2mo,  2  o 

Kemp's  Landscape  Gardening I2mo,  2  5O> 

Maynard's  Landscape  Gardening  as  Applied  to  Home  Decoration i2mo,  i  5 

Sanderson's  Insects  Injurious  to  Staple  Crops 121110,  i  s 

Insects  Injurious  to  Garden  Crops.     (In  preparation.) 
Insects  Injuring  Fruits.     (In  preparation.) 

Stockbridge's  Rocks  and  Soils 8vo,  2 

WolTs  Handbook  for  Farmers  and  Dairymen i6mo,  i  59 

ARCHITECTURE. 

Baldwin's  Steam  Heating  for  Buildings i2mo,  2  50- 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo- 

Birkmire's  Planning  and  Construction  of  American  Theatres 8vo,  3  oo 

Architectural  Iron  and  Steel 8vo,  3  50 

Compound  Riveted  Girders  as  Applied  in  Buildings 8vo,  2  oo 

Planning  and  Construction  of  High  Office  Buildings 8vo,  3  50 

Skeleton  Construction  in  Buildings 8vo,  3  oo 

Briggs's  Modern  American  School  Buildings 8vo,  4  oo 

Carpenter's  Heating  and  Ventilating  of  Buildings 8vo,  4  oo- 

Freitag's  Architectural  Engineering.     2d  Edition,  Rewritten 8vo,  3  50^ 

Fireproofing  of  Steel  Buildings 8vo,  2  50 

French  and  Ives's  Stereotomy 8vo,  2  50 

Gerhard's  Guide  to  Sanitary  House-inspection i6mo,  i  oo 

Theatre  Fires  and  Panics I2mo,  i  50 

1 


Hatfield's  American  House  Carpenter 8vo,  5  oo 

Holly's  Carpenters'  and  Joiners'  Handbook i8mo,  75 

Johnson's  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Kidder's  Architect's  and  Builder's  Pocket-book i6mo,  morocco,  4  oo 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Monckton's  Stair-building 4to,  4  oo 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  oo 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Sondericker's  Graphic  Statics  with  Applications  to  Trusses,  Beams,  and  Arches. 
(Shortly.) 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Woodbury's  Fire  Protection  of  Mills 8vo ,  2  50 

Worcester  and  Atkinson's  Small  Hospitals,  Establishment  and  Maintenance, 
Suggestions^for  Hospital  Architecture,  with  Plans  for  a  Small  Hospital. 

12010,  i  25 

The  World's  Columbian  Exposition  of  1893 Large  4to,  i  oo 


ARMY  AND,  NAVY. 

Bernadou's  Smokeless  Powder,  Nitro-cellulose,  and  the  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

*  Bruff's  Text-book  Ordnance  and  Gunnery 8vo,  6  oo 

Chase's  Screw  Propellers  and  Marine  Propulsion 8vo,  3  oo 

Craig's  Azimuth 4to,  3  So 

Crehore  and  Squire's  Polarizing  Photo-chronograph 8vo,  3  oo 

Cronkhite's  Gunnery  for  Non-commissioned  Officers 24010.  morocco,  2  oo 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  oo 

*  Sheep  7  50 

De  Brack's  Cavalry  Outpost  Duties.     (Carr.) 24010,  morocco,  2  oo 

Dietz's  Soldier's  First  Aid  Handbook i6mo,  morocco,  i  25 

*  Dredge's  Modero  French  Artillery 4to,  half  morocco,  15  oo 

Durand's  Resistance  and  Propulsion  of  Ships 8vo,  5  oo 

*  Dyer's  Handbook  of  Light  Artillery 12010,  3  oo 

Eissler's  Modern  High  Explosives .*.  ..*  :?".' 8vo,  4  oo 

*  Fiebeger's  Text-book  on  Field  Fortification Small  8vo,  2  oo 

Hamilton's  The  Gunner's  Catechism i8mo,  i  oo 

*  Hoff's  Elementary  Naval  Tactics 8vo,  i  50 

Ingalls's  Handbook  of  Problems  in  Direct  Fire 8vo,  4  oo 

*  Ballistic  Tables 8vo,  i  50 

*  Lyons's  Treatise  on  Electromagoetic  Phenomena.   Vols.  I.  and  II .  .  8vo,  each,  6  oo 

*  Mahan's  Permaoeot  Fortifications.     (Mercur.) 8vo,  half  morocco,  7  50 

Manual  for  Courts-martial 16010  morocco,  i  50 

*  Mercur's  Attack  of  Fortified  Places 12010,  2  oo 

*  '      Elements  of  the  Art  of  War 8vo,  4  oo 

Metcalf's^Cost  of  Manufactures — And  the  Admioistratioo  of  Workshops,  Public 

and  Private 8vo,  5  oo 

*  Ordnance  and  Gunnery . : 12010,  5  oo 

Murray's  lofaotry  Drill  Regulatioos 18010,  paper,  10 

*  Phelps's  Practical  Marioe  Surveyiog 8vo,  2  50 

Powell's  Army  Officer's  Examiner 12010,  4  oo 

Sharpe's  Art  of  Subsisting  Armies  in  War 18010,  morocco,  i   50 

2 


*  Walke's  Lectures  on  Explosives 8vo,  4  OO 

*  Wheeler's  Siege  Operations  and  Military  Mining 8vo,  2  oo 

Winthrop's  Abridgment  of  Military  Law I2mo,  2  50 

Woodhull's  Notes  on  Military  Hygiene i6mo,  i  50 

Young's  Simple  Elements  of  Navigation i6mo,  morocco,  i  oo 

Second  Edition,  Enlarged  and  Revised i6mo,  morocco  2  oo 


ASSAYING. 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

1 2 mo,  morocco,  i  50 

Furman's  Manual  of  Practical  Assaying 8vo,  3  oo 

Miller's  Manual  of  Assaying 12010,  i  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 

Hike's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

Wilson's  Cyanide  Processes I2mo,  i  50 

Chlorination  Process I2mo .  I  50 


ASTRONOMY. 

Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

raig's  Azimuth 4to,  3  50 

Doolittle's  Treatise  on  Practical  Astronomy 8vo,  4  oo 

Gore's  Elements  of  Geodesy 8vo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronomy .8vo,  3  oo 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

*  Michie  and  Harlow's  Practical  Astronomy 8vo,  3  oo 

*  White's  Elements  of  Theoretical  and  Descriptive  Astronomy 12  mo,  2  oo 


BOTANY. 

Davenport's  Statistical  Methods,  with  Special  Reference  to  Biological  Variation. 

i6mo,  morocco,  i  25 

Thome  and  Bennett's  Structural  and  Physiological  Botany i6mo,  2  25 

Westermaier's  Compendium  of  General  Botany.     (Schneider.) 8vo,  2  oo 


CHEMISTRY. 

Adriance's  Laboratory  Calculations  and  Specific  Gravity  Tables 12010,  /  25 

Allen's  Tables  for  Iron  Analysis 8vo,  3  oo 

Arnold's  Compendium  of  Chemistry.     (Mandel.)     (In  preparation.) 

Austen's  Notes  for  Chemical  Students I2mo,  i  50 

Bernadou's  Smokeless  Powder. — Nitro-cellulose,  and  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Bolton's  Quantitative  Analysis 8vo,  i  50 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  I  50 

Brush  and  Penfield's  Manual  of  Determinative  Mineralogy 8vo,  4  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.  (Boltwood.)  . . .  .8vo  3  oo 

Cohn's  Indicators  and  Test-papers i2mo,  2  oo 

Tests  and  Reagents 8vo,  3  oo 

Copeland's  Manual  of  Bacteriology.     (In  preparation.) 

Craft's  Short  Course  in  Qualitative  Chemical  Analysis.  (Schaeffer.). . . .  I2mo,  2  oo 

Drechsel's  Chemical  Reactions.     (Merrill.) 1 2mo,  i  25 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.)     (Shortly.) 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

3 


Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo 

Erdmann's  Introduction  to  Chemical  Preparations.     (Dunlap.) i2mo,  i  25 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

121110,  morocco,  i  50 

Fowler's  Sewage  Works  Analyses i2mo,  2  oo 

Fresenius's  Manual  of  Qualitative  Chemical  Analysis.     (Wells.) 8vo,  5  oo 

Manual  of  Qualitative  Chemical  Analysis.     Parti.    Descriptive.     (Wells.) 

8vo,  3  oo 

System  of  Instruction   in    Quantitative   Chemical  Analysis.      (Cohn.) 
2  vols.    (Shortly.) 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Furman's  Manual  of  Practical  Assaying 8vo,  3  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,  i  25 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     ( Woll.) i2mo,  2  oo 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel.) 8vo,  4  oo 

Helm's  Principles  of  Mathematical  Chemistry.     (Morgan.) 121110.  i  50 

Hinds's  Inorganic  Chemistry 8vo,  3  oo 

*  Laboratory  Manual  for  Students i2mo,  75 

Ho  lie  man's  Text-book  of  Inorganic  Chemistry.     (Cooper.) 8vo,  2  50 

Text-book  of  Organic  Chemistry.     (Walker  and  Mott.) 8vo,  2  50 

Hopkins's  Oil-chemists'  Handbook 8vo,  3  oo 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo,  i  oo 

Keep's  Cast  Iron 8vo,  2  50 

Ladd's  Manual  of  Quantitative  Chemical  Analysis i2mo.  i  oo 

Landauer's  Spectrum  Analysis.    (Tingle.) 8vo,  3  oo 

Lassar-Cohn's  Practical  Urinary  Analysis.     (Lorenz.) 12 mo,  i  oo 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control.     (In  preparation.) 

Lob's  Electrolysis  and  Electrosynthesis  of  Organic  Compounds.  (Lorenz.)  i2mo,  i  oo 

Mandel's  Handbook  for  Bio-chemical  Laboratory 12 mo,  i  50 

Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

3d  Edition,  Rewritten 8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) i2mo,  i  25 

Meyer's  Determination  of  Radicles  in  Carbon  Compounds.     (Tingle.). .  i2mo,  i  oo 

Miller's  Manual  of  Assaying i2mo,  i  oo 

Mixter's  Elementary  Text-book  of  Chemistry i2mo,  i  50 

Morgan's  Outline  of  Theory  of  Solution  and  its  Results i2mo,  i  oo 

Elements  of  Physical  Chemistry 121110.  2  oo 

Nichols's  Water-supply.     (Considered  mainly  from  a  Chemical  and  Sanitary 

Standpoint,  1883.) 8vo,  2  50 

O'Brine's  Laboratory  Guide  in  Chemical  Analysis 8vo,  2  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ost  and  Kolbeck's  Text-book  of  Chemical  Technology.     (Lorenz — Bozart.) 

(In  preparation.) 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 

Pictet's  The    Alkaloids   and   their   Chemical   Constitution.      (Biddle.)      (In 
preparation.) 

Pinner's  Introduction  to  Organic  Chemistry.     (Austen.) i2mo,  i  50 

Poole's  Calorific  Power  of  Fuels 8voy  3  oo 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Richards  and  Woodman's  Air  .Water,  and  Food  from  a  Sanitary  Standpoint .  8vo,  2  oo 

Richards's  Cost  of  Living  as  Modified  by  Sanitary  Science i2mo,  i  oo 

Cost  of  Food  a  Study  in  Dietaries i2mo,  i  oo 

*  Richards  and  Williams's  The  Dietary  Computer 8vo,  i  50 

Ricketts  and  Russell's  Skeleton  Notes  upon  Inorganic  Chemistry.     (Part  I. — 

Non-metallic  Elements.) 8vo,  morocco,  75 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 


d  eal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  oo 

Schimpf  s  Text-book  of  Volumetric  Analysis i2mo.  2  50 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco,  3  oo 

Handbook  for  Sugar  Manufacturers  and  their  Chemists. .  i6mo,  morocco,  2  oo 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

*  Descriptive  General  Chemistry 8vo  3  oo 

TreadwelTs  Qualitative  Analysis.     (HalL) 8vo,  3  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood.) i2tno,  i  50 

*  Walke's  Lectures  on  Explosive's 8vo,  4  oo 

Wells's  Laboratory  Guide  in  Qualitative  Chemical  Analysis 8vo,  i  50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students i2mo,  i   50 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Wiechmann's  Sugar  Analysis Small  8vo,  2  50 

Wilson's  Cyanide  Processes i2mo,  i  50 

Chlorination  Process .• ... .  .  i2mo .  i  50 

Wulling's  Elementary  Course  in  Inorganic  Pharmaceutical  and  Medical  Chem- 
istry  I2mo,  2  oo 


CIVIL  ENGINEERING. 

BRIDGES  AND    ROOFS.       HYDRAULICS.      MATERIALS    OF  ENGINEERING. 
RAILWAY  ENGINEERING. 

Baker's  Engineers'  Surveying  Instruments i2mo,  3  oo 

Bixby's  Graphical  Computing  Table Paper,  ig^X  24$  inches  25 

**  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal.     (Postage 

27  cents  additional.) 8vo,  n*.  3  50 

Comstock's  Field  Astronomy  for  Engineers 8vo,  ^  50 

Davis's  Elevation  and  Stadia  Tables 8vo,  I  oo 

Elliott's  Engineering  for  Land  Drainage i2mo,  I  50 

Practical  Farm  Drainage 121110,  i  oo 

FolwelTs  Sewerage.     (Designing  and  Maintenance.) 8vo,  3  oo 

Freitag's  Architectural  Engineering.     2d  Edition,  Rewritten 8vo,  3  50 

French  and  Ives's  Stereotomy 8vo,  2  50 

Goodhue's  Municipal  Improvements 1 2mo,  '  x  75 

Goodrich's  Economic  Disposal  of  Towns'  Refuse 8vo,  3  50 

Gore's  Elements  of  Geodesy 8vo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3  oo 

Howe's  Retaining  Walls  for  Earth i2mo,  i  25 

Johnson's  Theory  and  Practice  of  Surveying Small  8vo.  4  oo 

Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Kiersted's  Sewage  Disposal 121110,  i  25 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory.)  izmo,  2  oo 

Mahan's  Treatise  on  Civil  Engineering.     (1873,)    (Wood.) 8vo0  5  oo 

*       Descriptive  Geometry 8vo,  i  50 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Elements  of  Sanitary  Engineering 8vo,  2  oo 

Merriman  and  Brooks's  Handbook  for  Surveyors . 1 6mo,  morocco,  2  oo 

Nugent's  Plane  Surveying 8vo,  3  50 

Ogden's  Sewer  Design i2tno,  2  oo 

Patton's  Treatise  on  Civil  Engineering 8vo,  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Rideal'sJSewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  2  50 

5 


Sondericker's  Graphic  Statics,  wun  Applications  to   Trusses,  Beams,  ana 
Arches.     (Shortly.) 

*  Trantwine's  Civil  Engineer's  Pocket-book i6mo,  morocco,  5  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture,   8vo,  5^00 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

Webb's  Problems  in  the  U«e  and  Adjustment  of  Engineering  Instruments. 

i6mo,  morocco,  i  25 

*  Wheeler's  Elementary  Course  of  Civil  Engineering 8vo,  4  oo 

Wilson's  Topographic  Surveying 8vo,  3~5O 


BRIDGES  AND  ROOFS. 

Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges.  .8vo,  2  oo 

*         Thames  River  Bridge 4to,  paper,  5  oo 

Burr's  Course  on  the  Stresses  in  Bridges  and  Roof  Trusses,  Arched  Ribs,  and 

Suspension  Bridges 8vo,  3  50 

Du  Bois's  Mechanics  of  Engineering.     Vol.  II Small  4to,  10  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4to,  5  oo 

Fowler's  Coffer-dam  Process  for  Piers 8vo,  2  50 

Greene's  Roof  Trusses 8vo,  i  25 

Bridge  Trusses 8vo,  2  50 

Arches  in  Wood,  Iron,  and  Stone 8vo,  2  50 

Howe's  Treatise  on  Arches 8vo  4  oo 

Design  of  Simple  Roof -trusses  in  Wood  and  Steel 8vo,  2  oo 

Johnson,  Bryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures Small  4to,  10  oo 

Merriman  and  Jacoby's  Text-book  on  Roofs  and  Bridges: 

Part  I.— Stresses  in  Simple  Trusses 8vo,  2  50 

Part  II. — Graphic  Statics 8vo,  2  50 

Part  HI.— Bridge  Design.     4th  Edition,  Rewritten 8vo,  2  50 

Part  IV.— Higher  Structures 8vo,  2  50 

Morison's  Memphis  Bridge 4to,  10  oo 

Waddell's  De  Pontibus,  a  Pocket-book  for  Bridge  Engineers. . .  i6mo,  morocco,  3  oo 

Specifications  for  Steel  Bridges i2mo,  i  25 

Wood's  Treatise  on  the  Theory  of  the  Construction  of  Bridges  and  Roofs.Svo,  2  oo 
Wright's  Designing  of  Draw-spans: 

Part  I.  —Plate-girder  Draws 8vo,  2  50 

Part  II. — Riveted-truss  and  Pin-connected  Long-span  Draws 8vo,  2  50 

Two  parts  in  one  volume 8vo,  3  50 


HYDRAULICS. 

Bazin's  Experiments  upon  the  Contraction  of  the  Liquid  Vein  Issuing  from  an 

Orifice.     (Trautwine.) 8vo,  2  oo 

Bovey's  Treatise  on  Hydraulics 8vo,  5  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Diagrams  of  Mean  Velocity  of  Water  in  Open  Channels paper,  i  50 

Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  morocco,  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Folwell's  Water-supply  Engineering 8vo,  4  oo 

Frizell's  Water-power 8vo,  5  oo 

6 


Fuertes's  Water  and  Public  Health iimo,  I  50 

Water-filtration  Works 12010,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Hering  and  Trautwine.) 8vo,  4  oo 

Hazen's  Filtration  of  Public  Water-supply 8vo,  3  oo 

Hazlehurst's  Towers  and  Tanks  for  Water-works 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

Conduits 8vo,  2  oo 

Mason's    Water-supply.     (Considered    Principally   from    a   Sanitary   Stand- 
point.)    3d  Edition,  Rewritten 8vo,  4  oo 

Merriman's  Treatise  on  Hydraulics,     pth  Edition,  Rewritten 8vo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Schuyler's  Reservoirs  for  Irrigation,  Water-power,  and  Domestic   Water- 
supply Large  8vo,  5  oo 

**  Thomas  and  Watt's  Improvement  of  Riyers.     (Post.,  44  c.  additional),  4to,  6  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo.  5  oo 

Wegmann's  Desien  and  Construction  of  Dams 4to,  5  oo 

Water-suoolv  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Weisbach's  Hydraulics  and  Hydraulic  Motors.     (Du  Bois.) 8vo,  5  oo 

Wilson's  Manual  of  Irrigation  Engineering Small  8vo.  4  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,'  3  oo 

Wood's  Turbines 8vo,  2  50 

Elements  of  Analytical  Mechanics 8vo,  3  oo 


MATERIALS  OF  ENGINEERING. 

Baker's  Treatise  on  Masonry  Construction 8vo,  5  oo 

Roads  and  Pavements 8vo,  5  oo 

Black's  United  States  Public  Works Oblong  4to,  5  oo 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  So 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering.     6th  Edi- 
tion, Rewritten 8vo,  7  So 

Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

itfmo,  3  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Du  Bois's  Mechanics  of  Engineering.     VoL  I Small  4to,  7  50 

Johnson's  Materials  of  Construction Large  8vo,  6  oo 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Martens's  Handbook  on  Testing  Materials.     (Henning.)     2  vols 8vo,  7  50 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

Strength  of  Materials i2mo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users i2tno,  2  oo 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  oo 

Rockwell's  Roads  and  Pavements  in  France 1 2tno,  i  25 

Smith's  Wire :  Its  Use  and  Manufacture Small  4to,  3  oo 

Materials  of  Machines izmo,  i  oo 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Text-book  on  Roads  and  Pavements i2mo,  2  oo 

Thurston's  Materials  of  Engineering.    3  Parts 8vo,  8  oo 

Part  I. — Non-metallic  Materials  of  Engineering  and  Metallurgy 8vo,  2  oo 

Part  II. — Iron  and  Steel 8vo,  3  50 

Part  III. — A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2""so 

7 


Thurston's  Text-book  of  the  Materials  of  Construction 8vo,  5  oo 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

WaddelTs  De  Pontibus.     (A  Pocket-book  for  Bridge  Engineers.) . .  i6mo,  mor.,  3  oo 

Specifications  for  Steel  Bridges i2mo,  i  25 

Wood's  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on  the  Pres- 
ervation of  Timber 8vo,  2  oo 

Elements  of  Analytical  Mechanics 8vo,  3  oo 


RAILWAY  ENGINEERING. 

Andrews's  Handbook  for  Street  Railway  Engineers.     3X5  inches,  morocco,  i  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brooks's  Handbook  of  Street  Railroad  Location i6mo.  morocco,  i  50 

Butts's  Civil  Engineer's  Field-book i6mo,  morocco,  2  50 

Crandall's  Transition  Curve i6mo,  morocco,  i  50 

Railway  and  Other  Earthwork  Tables 8vo,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.    i6mo,  morocco,  4  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:   (1879) Paper,  5  oo 

*  Drinker's  Tunneling,  Explosive  Compounds,  and  Rock  Drills,  4to,  half  mor.,    25  oo 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide i6mo,  mor.,  2  50 

Howard's  Transition  Curve  Field-book i6mo  morocco  i  50 

Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments    8vo,  i   oo 

Molitor  and  Beard's  Manual  for  Resident  Engineers i6mo,  i  oo 

Nagle's  Field  Manual  for  Railroad  Engineers i6mo,  morocco.  *  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  morocco,  3  oo 

Pratt  and  Alden's  Street-railway  Road-bed 8vo,  2  oo 

Searles's  Field  Engineering i6mo,  morocco,  3  oo 

Railroad  Spiral i6mo,  morocco  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*  Trautwine's  Method  of  Calculating  the  Cubic  Contents  of  Excavations  and 

Embankments  by  the  Aid  of  Diagrams 8vo,  2  oo 

he  .Field  Practice  of  [Laying   Out    Circular    Curves    for   Railroads. 

i2mo,  morocco,  2  50 

*  Cross-section  Sheet Paper,  25 

^ebb's  Railroad  Construction.     2d  Edition,  Rewritten i6mo.  morocco,  5  oo 

"Wellington's  Economic  Theory  of  the  Location  of  Railways Small  8vo,  5  oo 


DRAWING. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jones's  Machine  Design: 

Part  I. — Kinematics  of  Machinery 8vo,  i  50 

Part  II. — Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

MacCord's  Elements  of  Descriptive  Geometry 8vo,  3  oo 

Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting 8vo,  i  50 

Industrial  Drawing.    (Thompson.) 8vo,  3  50 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

8 


Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design.  .8vo,  3  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  2  50 

Warren's  Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing. .  i2mo, 


Drafting  Instruments  and  Operations i2mo, 

Manual  of  Elementary  Projection  Drawing i2mo, 

Manual  of  Elementary  Broblems  in  the  Linear  Perspective  of  Form  and 


Shadow i2mo,  oo 

Plane  Problems  in  Elementary  Geometry i2mo,  25 

Primary  Geometry i2mo,  75 

Elements  of  Descriptive  Geometry,  Shadows,  and.Perspective 8vo,  3  So 

General  Problems  of  Shades  and  Shadows 8vo,  3  oo 

Elements  of  Machine  Construction  and  Drawing 8vo,  7  5° 

Problems.  Theorems,  and  Examples  in  Descriptive  Geometrv 8vo,  2  50 

Weisbach's  Kinematics  and  the  Power  of  Transmission.       (Hermann  an'' 

Klein.) 8vo,  5  oo 

Whelpley's  Practical  Instruction  in  the  Art  of  Letter  Engraving i2mo,  2  oo 

Wilson's  Topographic  Surveying 8vo,  3  So 

Free-hand  Perspective 8vo,  2  50 

Free-hand  Lettering.     (In  preparation.) 

Woolf's  Elementary  Course  in  Descriptive  Geometry Large  8vo,  3  oo 


'ELECTRICITY  AND   PHYSICS. 

Anthony  and  Brackett's  Text-book  of  Physics.  (Magie.) Small  8vo,  3  oo 

Anthony's  Lecture-notes  on  the  Theory  of  Electrical  Measurements 12 mo,  i  oo 

Benjamin'slHistory  of  Electricity 8vo,  3  oo 

Voltaic  Cell 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.  (Boltwood.).  .8vo,  3  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph ' 8vo,  3  oo 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book. .  lomo,  morocco,  4  oo 

blather's  Dvnamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Gilbert's  De  Magnete.  (Mottelay.) 8vo,  2  50 

Holman's  Precision  of  Measurements 8vo,  2  oo 

Telescopic  Mirror-scale  Method,  Adjustments,  and  Tests Large  8vo  75 

Lanaauer's  Spectrum  Analysis.  (Tingle.) 8vo,  3  oo 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard — Burgess.  )i2mo,  3  OO 

Lob's  Electrolysis  and  Electrosynthesis  of  Organic  Compounds.  (Lorenz.)  i2mo,  i  oo 

*  Lyons's  Treatise  on  Electromagnetic  Phenomena.     Vols.  I.  and  11.  8vo,  each,*  61  oo 

*  Michie.     Elements  of  Wave  Motion  Relating  to  Sound.'and  Light 8vo,_£  op 

Niaudet's  Elementary  Treatise  on  Electric  Batteries.     (FishoacK. ) i2mo,  2  50 

*  Parshall  and  Hobart's  Electric  Generators Small  4to.  half  morocco,  10  oo 

*  Rosenberg's  Electrical  Engineering.   (HaldaneGee — Kinzbrunner.) 8vo,  i  50 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     (In  preparation-' 

Thurston's  Stationary  Steam-engines .^ 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Small  8vo,  2  oo 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 


LAW. 

*iDavis's  Elements  of  Law 8vo,  2  50 

*          Treatise  on  the  Military  Law  of  United  States 8vo,  7  oo 

Sheep,  7  So 

Manual  for  Courts-martial i6mo,  morocco,  i  50 

9 


Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering'and  Archi- 
tecture      8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Winthrop's  Abridgment  of  Military  Law 12010,  a  50 


MANUFACTURES. 

Bernadou's  Smokeless  Powder — Nitro-cellulose  and  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Holland's  Iron  Founder i2mo,  2  50 

"  The  Iron  Founder,"  Supplement i2mo,  2  50 

Encyclopedia  of  Founding  and  Dictionary  of^Foundry  Terms  Used.in  the 

Practice  of  Moulding i2mo,  3  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo 

Fitzgerald's  Boston  Machinist i8mo,  i  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

Hopkins's  Oil-chemists'  Handbook 8vo,  3  oo 

Keep's  Cast  Iron 8vo,  a  50 

Leach's  The  Inspection  and  Analysis  of  Food  with  Specia£Reference  to  State 

Control.     (In  preparation.) 

Metcalf's  SteeL    A  Manual  for  Steel-users i2mo,  2  oo 

Metcalfe's  Cost  of  Manufactures— And  the  Administration    of  Workshops, 

Public  and  Private 8vo,  5  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

Wire:  Its  Use  and  Manufacture Small  4to,  3  oo 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco,  3  oo 

Handbook  tor  sugar  Manufacturers  and  their  Chemists.. .  i6mo,  morocco,  2  oo 
Thurston's  Manual  of  Steam-boilers,  their  Designs,  Construction  and  Opera- 
tion  8vo,  5  oo 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

West's  American  Foundry  Practice I2mo,  a  50 

Moulder's  Text-book i2mo,  2  50 

Wiechmann's  Sugar  Analysis Small  8vo,  a  50 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Woodbury's  Fire  Protection  of  Mills 8vo,  a  50 


MATHEMATICS. 

Baker's  Elliptic  Functions 8vo,  i  50 

*  Bass's  Elements  of  Differential  Calculus i2mo,  4  oo 

Briggs's  Elements  of  Plane  Analytic  Geometry 12 mo,  oo 

Chapman's  Elementary  Course  hi  Theory  of  Equations i2mo,  50 

Compton's  Manual  of  Logarithmic  Computations i2mo,  50 

Davis's  Introduction  to  the  Logic  of  Algebra 8vo,  50 

*  Dickson's  College  Algebra Large  i2mo,  50 

*  Introduction  to  the  Theory  of  Algebraic  Equations   Largeli2mo,  25 

Halsted's  Elements  of  Geometry 8vo,  75 

Elementary  Synthetic  Geometry 8vo.  50 

10 


*  Johnson's  Three-place  Logarithmic  Tables:    Vest-pocket  size paper,  '     15 

100  copies  for  5  oo 

*  Mounted  on  heavy  cardboard,  8  X 10  inches,  25 

10  copies  for  2  oo 

Elementary  Treatise  on  the  Integral  Calculus Small  8vo,  i  50 

Curve  Tracing  in  Cartesian  Co-ordinates izmo,  I  oo 

Treatise  on  Ordinary  and  Partial  Differential  Equations Small  8vo,  3  5<> 

Theory  of  Errors  and  the  Method  of  Least  Squares I2mo,  I  50 

»        Theoretical  Mechanics I2mo,  3  oo 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory.)  I2mo,  200 

*  Ludlow  and  Bass.     Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo,  3  oo 

Trigonometry  and  Tables  published  separately Each,  2  oo 

Maurer's  Technical  Mechanics.     (In  preparation.) 

Merriman  and  Woodward's  Higher  Mathematics 8vo,  5  oo 

Merriman's  Method  of  Least  Squares 8vo,  2  oo 

Rice  and  Johnson's  Elementary  Treatise  on  the  Differential  Calculus. Sm.,  8vo,  3  oo 

Differential  and  Integral  Calculus.     2  vols.  in  one Gziall  8vo,  2  50 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,  2  oo 

Trigonometry:  Analytical,  Plane,  and  Spherical i2mo,  i  oo 

MECHANICAL   ENGINEERING. 
MATERIALS  OF  ENGINEERING,  STEAM-ENGINES  AND  BOILERS. 

Baldwin's  Steam  Heating  for  Buildings I2mo,  2  50 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

Benjamin's  Wrinkles  and  Recipes I2mo,  2  oo 

Carpenter's  Experimental  Engineering 8vo,  6  oo 

Heating  and  Ventilating  Buildings 8vo,    4  oo 

Clerk's  Gas  and  Oil  Engine Small  8vo,    4  oo 

Coolidge's  Manual  of  Drawing 8vo,    paper,    i  oo 

Cromwell's  Treatise  on  Toothed  Gearing 1 21x10 ,    i  50 

Treatise  on  Belts  and  Pulleys I2mo,    i  50 

Durley's  Kinematics  of  Machines 8vo,    4  oo 

F lather's  Dynamometers  and  the  Measurement  of  Power 12 mo,    3  oo 

Rope  Driving i2mo,    2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,    i  25 

Hall's  Car  Lubrication I2mo,    i  oo 

Button's  The  Gas  Engine.     (In  preparation.) 
Jones's  Machine  Design: 

Part  I. — Kinematics  of  Machinery 8vo,    i  50 

Part  II. — Form,  Strength,  and  Proportions  of  Parts 8vo,    3  oo 

Kent's  Mechanical  Engineer's  Pocket-book i6mo,    morocco,  5  oo 

Kerr's  Power  and  Power  Transmission 8vo,    2  oo 

MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,    5  oo 

Mechanical  Drawing 4to,    4  oo 

Velocity  Diagrams 8vo,    i  50 

Mahan's  Industrial  Drawing.    (Thompson.) 8vo,    3  50 

Poole's  Calorific  Power  of  Fuels 8vo,    3  oo 

Reid's  Course  in  Mechanical  Drawing 8vo.    2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design . .  8vo,    3  oo 

Richards's  Compressed  Air 12010,    i  50 

Robinson's  Principles  of  Mechanism 8vo,   3  oo 

Smith's  Press-working  of  Metals 8vo     3  oo 

Thurston's  Treatise  on   Friction  and    Lost  Work  in   Machinery  and   Mil 

Work 8vo,    3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics .  1 2  mo ,    i  oo 

11 


Warren's  Elements  of  Machine  Construction  and  Drawing Svo,  7  50 

Weisbach's  Kinematics  and  the  Power  of  Transmission.      Herrmann — 

Klein.) 8vo,  5  oo 

Machinery  of  Transmission  and  Governors.     (Herrmann — Klein.). . Svo,  5  oo 

HydrauUcs  and  Hydraulic  Motors.     (Du  Bois.) 8vo,  5  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines 8vo,  2  50 

MATERIALS  OF  ENGINEERING. 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering.     6th  Edition, 

Reset 8vo,  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Johnson's  Materials  of  Construction . . Large  8vo,  6  oo 

Keep's  Cast  Iron : Svo  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Martens's  Handbook  on  Testing  Materials.     (Henning.) 8vo,  7  50 

Merriman's  Text-book  on  the  Mechanics  of  Materials Svo,  4  oo 

Strength  of  Materials i2mo,  i  oo 

Metcalf's  Steel.    A  Manual  for  Steel-users i2mo.  2  oo 

Smith's  Wire:  Its  Use  and  Manufacture Small  4to,  3  oo 

Materials  of  Machines i2mo,  i  oo 

Thurston's  Materials  of  Engineering 3  vols. ,  Svo  8  oo 

Part   II.— Iron  and  Steel Svo,  3  So 

Part  IH.— A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents Svo,  2  50 

Text-book  of  the  Materials  of  Construction Svo  5  oo 

Wood's  Treatise  on  the  Resistance  of  Materials  and  an  Appendix  on  the 

Preservation  of  Timber Svo,  2  oo 

Elements  of  Analytical  Mechanics 8vo,  3  oo 


STEAM-ENGINES  AND  BOILERS. 

Carnot's  Reflections  on  the  Motive  Power  of  Heat.     (Thurston.) 12 mo,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  .i6mo,  mor.,  4  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

Goss's  Locomotive  Sparks 8vo,  2  oo 

Hemenway's  Indicator  Practice  and  Steam-engine  Economy i2mo,  2  oo 

Button's  Mechanical  Engineering  of  Power  Plants Svo,  5  oo 

Heat  and  Heat-engines Svo,  5  oo 

Kent's  Steam-boiler  Economy Svo,  4  oo 

Kneass's  Practice  and  Theory  of  the  Injector Svo.  i  50 

MacCord's  Slide-valves Svo,  2  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Peabody's  Manual  of  the  Steam-engine  Indicator i2mo,  i  50 

Tables  of  the  Properties  of  Saturated  Steam  and  Other  Vapors Svo,  i  oo 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines Svo,  5  oo 

Valve-gears  for  Steam-engines Svo,  2  50 

Peabody  and  Miller's  Steam-boilers Svo,  4  oo 

Pray'a  Twenty  Years  with  the  Indicator Large  Svo,  2  50 

Pupln's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg.) i2mo.  i  25 

Reagan's  Locomotives :  Simple,  Compound,  and  Electric i2mo,  2  50 

Rontgen's  Principles  of  Thermodynamics.     (Du  Bois.) Svo,  5  oo 

Sinclair's  Locomotive  Engine  Running  and  Management 12 mo,  2  oo 

Smart's  Handbook  of  Engineering  Laboratory  Practice i2mo,  2  50 

Snow's  Steam-boiler  Practice Svo,  3  oo 

12 


Spangler's  Valve-gears 8vo,  a  50 

Notes  on  Thermodynamics I2mo,  i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Handy  Tables 8vo.  i   50 

Manual  of  the  Steam-engine 2  vols..  8vo     10  oo 

Part  I. — History,  Structuce,  and  Theory 8vo,  6  oo 

Part  II. — Design,  Construction,  and  Operation 8vo,  6  oo 

Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indicator  and 

the  Prony  Brake 8vo  5  oo 

Stationary  Steam-engines 8vo,  2  50 

Steam-boiler  Explosions  in  Theory  and  in  Practice i2mo,  i  50 

Manual  of  Steam-boilers ,  Their  Designs,  Construction,  and  Operation .  8vo,  5  oo 

Weisbach's  Heat,  Steam,  a  <J  Steam-engines.     (Du  Bois.) 8vo,  5  oo 

Whitham's  Steam-engine  I  ^sign 8vo,  5  oo 

Wilson's  Treatise  on  Steam-boilers.     (Flather.) i6mo,  2  50 

Wood's  Thermodynamics.  Heat  Motors,  and  Refrigerating  Machines 8vo,  4  oo 


MECHANICS    \ND   MACHINERY. 

Barr's  Kinematics  ot  Machinery 8vo,    2~5O 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,    7  50 

Chase's  The  Art  of  Pattern-making I2mo,    2  SO 

Chordal. — Extracts  from  Letters 12010,    2  oo 

Church's  Mechanics  of  Engineering 8vo     6  oo 

Notes  and  Examples  in  Mechanics 8vo.    2  oo 

Compton's  First  Lessons  in  Metal-working i amo,    i  50 

Compton  and  De  Groodt's  The  Speed  Lathe I2mo,    I  50 

Cromwell's  Treatise  on  Toothed  Gearing I2mo,    I  50 

Treatise  on  Belts  and  Pulleys I2mo,    i  50 

Dana's  Text-book  of  Elementary  Mechanics  for  the  Use  of  Colleges  and 

Schools i2mo,    i  50 

Dingey's  Machinery  Pattern  Making I2mo,    a  oo 

Dredge's  Record  of  the  Transportation  Exhibits  Building  of  the   World's 

Columbian  Exposition  of  1893 4to,  half  morocco,    5  oo 

Du  Bois's  Elementary  Principles  of  Mechanics: 

Vol.     I. — Kinematics 8vo,    3  50 

Vol.   II. — Statics 8vo,    4  oo 

Vol.  III. — Kinetics 8vo,    3  50 

Mechanics  of  Engineering.     Vol.  I .Small  4to,      7  50 

VoL  H Small  4to,    10  oo 

Durley's  Kinematics  of  Machines 8vo,    4  oo 

Fitzgerald's  Boston  Machinist i6mo,    I  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power lamo,    3  oo 

Rope  Driving 1 2mo ,    2  oo 

Goss'g  Locomotive  Sparks 8vo,    2  oo 

Hall's  Car  Lubrication I2mo,    I  oo 

Eolly's  Art  of  Saw  Filing i8mo         75 

*  Johnson's  Theoretical  Mechanics 1 2mo,    3  oo 

Statics  by  Graphic  and  Algebraic  Methods 8vo,    2  oo 

Jones's  Machine  Design: 

Part  I. — Kinematics  of  Machinery 8vo,    i  50 

Part  II. — Form,  Strength,  and  Proportions  of  Parts 8vo,    3  oo 

Kerr's  Power  and  Power  Transmission 8vo,    a  oo 

Lanza's  Applied  Mechanics 8vo,    7  50 

MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,   5  oo 

Velocity  Diagrams 8ro,    I  50 

Maurer's  Technical  Mechanics.     (In  preparation.) 

13 


Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

*  Michie's  Elements  of  Analytical  Mechanics Svo,  4  oo 

Reagan's  Locomotives:  Simple,  Compound,  and  Electric izmo,  2  50 

Reid's  Courselin  Mechanical  Drawing 8vo,  2  oo 

Text-book  ofMechanical  Drawing  and  Elementary  Machine  Design .  .  8vo,  3  oo 

Richards's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     (In  preparation.) 

Sinclair's  Locomotive-engine  Running  and.Management • i2mo,  2  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

A      Materials  of  Machines i2mo,  i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Treatise  on  Friction  and  Lost  Work  in  Machinery  and  Mill 

Work 8vo,  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics.  i2mo,  i  oo 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Weisbach's    Kinematics  I  and    the   Power  of    Transmission.     (Herrmann — 

Klein.) 8vo,  5  oo 

Machinery  of  Transmission  and  Governors.     (Herrmann — Klein. ).8vo,  5  oo 

Wood's  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Principles  of  Elementary  Mechanics i2mo,  i  25 

Turbines 8vo,  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

METALLURGY. 

Egleston's  Metallurgy  of  Silver,  Gold,  and  Mercury: 

Vol.   I.— Silver 8vo,  7  50 

Vol.   II. — Gold  and  Mercury 8vo,  7  50 

**  Iles's  Lead-smelting.     (Postage  9  cents  additional.) i2mo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe 8vo,  i  50 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard — Burgess.) .  i2mo,  3  oo 

Metcalf 's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Smith's  Materials  of  Machines i2mo,  i  oo 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  oo 

Part  II. — Iron  and  Steel 8vo,  3  50 

Part  III. — A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

MINERALOGY. 

Barringer's  Description  of  Minerals  of  Commercial  Value.     Oblong,  morocco,  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,"  3  oo 

Map  of  Southwest  Virginia Pocket-book  form,  2  oo 

Brush's  Manual  of  Determinative  Mineralogy.     (Penfield.). 8vo,  4  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

Dictionary  of  the  Names  of  Minerals 8vo,  3  50 

Dana's  System  of  Mineralogy Large  8vo,  half  leather,    12  50 

First  Appendix  to  Dana's  New  "System  of  Mineralogy." Large  8vo,  i  oo 

Text-book  of  Mineralogy 8vo,  4  oo 

Minerals  and  How  to  Study  Them 121110,  i  50 

Catalogue  of  American  Localities  of  Minerals Large  8vo,  i  oo 

Manual  of  Mineralogy  and  Petrography i2mo,  2  oo 

Egleston's  Catalogue  of  Minerals  and  Synonyms 8vo,  2  50 

Hussak's  The  Determination  of  Rock-forming  Minerals.     (Smith.)  Small  8vo,  2  oo 

14 


*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  o  50 
Rosenbusch's   Microscopical   Physiography   of   the    Rock-making    Minerals. 

(Iddings.) 8vo,  5  oo 

*  Tillman's  Text-book  of  Important  Minerals  and  Docks 8vo,  2  oo 

Williams's  Manual  of  Lithology 8vo,  3  oo 


MINING. 

Beard's  Ventilation  of  Mines i2mo,  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,  3  oo 

Map  of  Southwest  Virginia Pocket-book  form,  2  oo 

*  Drinker's  Tunneling,  Explosive  Compounds,  and  Rock  Drills. 

4to,  half  morocco,  25  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Fowler's  Sewage  Works  Analyses Z2mo,  oo 

Goodyear's  Coal-mines  of  the  Western  Coast  of  the  United  States 12010,  50 

Ihlseng's  Manual  of  Mining .    , 8vo,  oo 

**  Iles's  Lead-smelting.     (Postage  QC.  additional.) I2mo,  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe 8vo,  50 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  oo 

*  Walke's  Lectures  on  Explosives 8vo,  oo 

Wilson's  Cyanide  Processes I2mo,  50 

Chlorination  Process i2mo,  50 

Hydraulic  and  Placer  Mining 12010,  oo 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation 12 mo,  25 


SANITARY  SCIENCE. 

Copeland's  Manual  of  Bacteriology.     (In  preparation.) 

Folwell's  Sewerage.     (Designing,  Construction,  and  Maintenance.; 8vo,  3  oo 

Water-supply  Engineering 8vo,  4  oo 

Fuertes's  Water  and  Public  Health 1 2 mo,  i  50 

Water-filtration    Works I2mo,  2  50 

Gerhard's  Guide  to  Sanitary  House-inspection i6mo,  i  oo 

Goodrich's  Economical  Disposal  of  Town's  Refuse Demy  8vo,  3  50 

Hazen's  Filtration  of  Public  Water-supplies 8vo,  3  oo 

Kiersted's  Sewage  Disposal i2mo,  i  25 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control.     (In  preparation.') 

Mason's   Water-supply.     (Considered   Principally   from   a   Sanitary   Stand- 
point.)   3d  Edition,  Rewritten 8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) i2mo,  I  25 

Merriman's  Elements  of  Sanitary  Engineering 8vo,  2  oo 

Nichols's  Water-supply.     (Considered  Mainly  from  a  Chemical  and  Sanitary 

Standpoint.)     (1883.) 8vo,  2  50 

Ogden's  Sewer  Design 1 2010,  2  oo 

*  Price's  Handbook  on  Sanitation I2mo,  i  50 

Richards's  Cost  of  Food.     A  Study  in  Dietaries i2mo,  i  oo 

Cost  of  Living  as  Modified  by  SanitarylScience 12 mo,  i  oo 

Kichards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Stand- 
point  8vo,  2  oo 

*  Richards  and  Williams's  The  Dietary'Computer 8vo,  i  50 

Rideal's  Sewage  and  Bacterial  Purification  of  Sewage 8vo,  3  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Woodhull's  Notes'and  Military  Hygiene i6mo,  i  50 

15 


MISCELLANEOUS. 

Barker's  Deep-sea  Soundings 8vo,  2  oo 

Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo,  i  50 

FerrePs  Popular  Treatise  on  the  Winds 8vo,  4  oo 

Haines's  American  Railway  Management i2mo,  2  50 

Mott's  Composition.'Digestibility ,  and  Nutritive  Value  of  Food.    Mounted  chart,  i  25 

Fallacy  of  the  Present  Theory  of  Sound i6mo,  i  oo 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute,  1824-1894.  Small  8vo,  3  oo 

Rotherham's  Emphasized  New  Testament Large  8vo,  2  oo 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo,  3  50 

Totten's  Important  Question  in  Metrology 8vo,  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

Worcester  and  Atkinson.     Small  Hospitals,  Establishment  and  Maintenance, 
and  Suggestions  for  Hospital  Architecture,  with  Plans  for  a  Small 

Hospital I2mo,  i  25 

HEBREW  AND  CHALDEE    TEXT-BOOKS. 

Green's  Grammar  of  the  Hebrew  Language 8vo,  3  oo 

Elementary  Hebrew  Grammar i2mo,  i  25 

Hebrew  Chrestomathy 8vo,  2  oo 

Gesenius's  Hebrew  and  Chaldee  Lexicon  to  the  Old  Testament  Scriptures. 

(Tregelles.) Small  4to,  half  morocco,  5  oo 

Letteris's  Hebrew  Bible 8vo,  2  25 

16 


14  DAY  USE 

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